f 


THE 


GAS    AND    OIL    ENGINE  , 


BY 


DUGALD    CLERK 


ASSOCIATE   MEMBER   OF   THE   INSTITUTION   OF   CIVIL   ENGINEERS 

FELLOW   OF   THE   CHEMICAL  SOCIETY  :    MEMBER   OF   THE  ROYAL   INSTITUTION 

FELLOW  OF   THE   INSTITUTE   OF   PATENT   AGENTS 


SEVENTH     EDITION 

REVISED    AND    ENLARGED   (1896) 


LONGMANS,  GREEN,  AND  CO, 

39    PATERNOSTER     ROW,     LONDON 
NEW  YORK  AND  BOMBAY 
1897 


All    rights     reserved 


c> 


PREFACE 

TO 

THE     SIXTH     EDITION. 


MANY  important  changes  have  been  made  in  the  constructive 
details  of  gas  engines  since  the  first  part  of  this  work  was  pub- 
lished, and  oil  engines  using  heavy  oil  have  become  practicable 
motors,  so  that  it  has  become  necessary  to  bring  the  informa- 
tion in  this  book  thoroughly  up  to  date.  In  doing  this  the  author 
thought  it  better  to  make  additions  rather  than  alterations  on  the 
original,  and  accordingly  the  first  part  of  the  book  is  retained  in 
its  original  form,  and  two  parts  have  been  added  :  the  second 
part  deals  with  modern  gas  engines,  both  impulse-every-revolution 
and  Otto  cycle  ;  and  the  third  part  deals  with  the  oil  engine.  The 
first  part  of  the  book  thus  remains  in  the  form  in  which  it  is 
familiar  to  many  engineers  ;  indeed,  the  author  may  say  with  truth 
all  engineers  interested  in  the  gas  engine  throughout  the  world, 
because  the  book  has  been  translated  and  published  in  German, 
and  many  parts  extracted  in  French  works,  while  it  is  largely  used 
in  America  both  by  engineers  and  in  the  engineering  classes  of 
the  Universities. 

In  dealing  with  the  various  engines  the  author  has  drawn 
upon  his  personal  experience  of  gas  and  oil  engines,  now  extending 


vi  The  Gas  Engine 

over  twenty  years,  and  he  has  endeavoured  to  discuss  the  various 
points  involved  in  a  dispassionate  manner,  pointing  out  to  the 
engineer  the  difficulties  as  well  as  the  advantages  peculiar  to  each 
construction  or  type.  This  is  very  necessary  if  moderately  rapid 
advance  is  to  be  made,  and  it  appears  to  the  author  most  un- 
desirable to  adopt  the  tone  so  often  found  in  engineering  literature 
of  indiscriminate  admiration  of  this  or  that  firm's  wonderful  motor, 
when  in  reality  the  motor  discussed  in  so  far  as  it  departs  from 
standard  practice  is  not  an  improvement,  but  the  reverse.  The 
author  has  accordingly  freely  criticised  any  points  which  appear 
to  him  defective  in  the  various  engines. 

In  this  edition  special  attention  has  been  paid  to  the  oil 
engine,  in  view  of  its  rapid  rate  of  present  development  and  the 
probability  of  its  very  extensive  use  for  many  new  purposes,  such 
as  motor  cars.  Many  engineers  are  now  paying  attention  to  the 
oil  engine,  to  whom  the  subject  is  unfamiliar  ;  and  in  the  hope  of 
proving  useful  to  such  new  men  on  the  work,  the  author  has  gone 
carefully  into  the  discussion  of  the  chemical  nature  of  petroleum 
and  the  different  methods  of  vaporising  heavy  oils. 

In  dealing  with  the  oil  engine  the  author  has  freely  availed 
himself  of  the  careful  experiments  on  oil  engines  by  the  engineers 
for  the  Royal  Agricultural  Society's  Show  at  the  Cambridge 
Meeting.  The  author  has  made  many  tests  himself ;  but  as  these 
were  mostly  made  in  the  course  of  his  professional  work  and  were 
confidential,  he  has  chosen  for  discussion  the  publicly  made  tests 
and  descriptions  rather  than  his  personal  tests. 

In  concluding,  the  author  expresses  his  thanks  to  the  Council 
of  the  Institution  of  Civil  Engineers  for  the  use  of  illustrations 
from  papers  by  Professor  Unwin  and  Mr.  J.  E.  Dowson,  published 
in  the  valuable  Minutes  of  the  Institution,  and  also  for  extracts  of 


Preface  to  the  Sixth  Edition  vii 

tests  by  Mr.  Dowson,  and  tables  by  the  author,  also  published  in 
Institution  papers. 

The  author  also  thanks  the  various  makers  of  gas  and  oil 
engines  who  have  allowed  him  to  test  their  engines  for  the 
purposes  of  this  book,  and  who  have  lent  him  blocks  ;  among  those 
makers  are  Messrs.  Crossley  Bros.  Limited,  J.  E.  H.  Andrew 
&  Co.  Limited,  T.  B.  Barker  &  Co.,  Tangyes,  Limited,  Robey 
&  Co.  Limited,  Wells  Bros.,  Hornsby  &  Sons,  Fielding  &  Platt, 
Mr.  Peter  Burt,  and  Mr.  Bellamy  of  Andrew  &  Co. 

Many  of  the  drawings  for  the  book,  however,  have  been  made 
by  the  author's  draughtsmen  directly  from  the  engines. 

In  the  Appendix  the  author  has  added  a  complete  list  of 
British  gas  and  oil  engine  patents  from  1791  to  the  end  of  1893. 
All  the  English  specifications  from  1876,  including  this  year,  are 
in  the  author's  possession,  and  he  will  be  very  pleased  to  freely 
allow  those  interested  access  to  them. 

D.   C. 

18  SOUTHAMPTON  BUILDINGS,  CHANCERY  LANE, 
LONDON  :  June  1896. 


PREFACE 

TO 

THE     FIRST     EDITION. 


IN  this  work  the  author  has  endeavoured  to  systematise  the  know- 
ledge in  existence  upon  the  subject,  and  to  explain  the  science 
and  practice  of  the  Gas  Engine  in  a  way  which  he  hopes  may  be 
useful  to  the  engineer. 

The  historical  sketch  with  which  the  book  opens  proves  that, 
like  other  great  subjects,  the  gas  engine  has  long  occupied  men's 
minds. 

The  first  six  chapters  treat  of  theory,  including  the  distin- 
guishing features  of  the  gas  engine  method,  classification,  thermo- 
dynamics of  the  various  types,  and  the  chemical  and  physical 
phenomena  of  combustion  and  explosion. 

In  the  seventh  chapter,  standard  engines  illustrative  of  the 
different  types  are  described,  and  tests  from  each  engine  for  power 
and  consumption  of  gas  are  given.  The  diagrams  and  efficiencies 
are  shortly  discussed,  compared  with  theory,  and  the  various  sources 
of  loss  pointed  out. 

The  eighth  chapter  deals  with  typical  igniting  arrangements, 
and  the  ninth  with  governing  gear  and  other  mechanical  details. 


x  Preface  to  the  First  Edition 

The  tenth  chapter  briefly  describes  and  discusses  various 
theories  which  have  been  propounded  concerning  the  action  of 
the  gases  in  the  cylinder  of  the  gas  engine  and  in  gaseous  explo- 
sions. 

In  the  last  chapter  the  great  sources  of  loss  of  heat  still 
existing  in  the  best  gas  engines  are  discussed,  with  the  object  of 
pointing  out  the  way  still  open  for  further  advance. 

Many  of  the  tests  and  most  of  the  theoretical  and  practical 
discussion,  result  from  the  author's  personal  experience  with  the 
gas  engine. 

In  the  chapter  on  thermodynamics  the  author  is  much  indebted 
to  the  work  of  the  late  Prof.  RANKINE,  and  he  has  adopted,  in 
treating  of  efficiency,  some  of  the  elegant  formulae  of  Dr.  AIME 
WITZ,  of  Lille,  to  whom  as  well  as  to  Prof.  SCHOTTLER  and  Prof. 
THURSTON  he  has  much  pleasure  in  expressing  his  indebtedness. 

D,  C. 

BIRMINGHAM  :  July  1886. 


CONTENTS. 


PART   I. 
THE  GAS  ENGINE    UP    TO   THE    YEAR   1886. 

CHAPTER  PAGE 

HISTORICAL  SKETCH  OF  THE  GAS  ENGINE,  1690  TO  1886  .  i 

I.     THE  GAS  ENGINE  METHOD     .        .        ,        .  •     .        ...  23 

II.     GAS  ENGINES  CLASSIFIED    .        .        ...        .        .29 

III.  THERMODYNAMICS  OF  THE  GAS  ENGINE        .        .        .     .  36 

IV.  THE  CAUSES  OF  Loss  IN  GAS  ENGINES      .        .        .        .  .  72 
V.     COMBUSTION  AND  EXPLOSION     ...        ..        ...      .     .  79 

VI.     EXPLOSION  IN  A  CLOSED  VESSEL 95 

VII.     THE  GAS  ENGINES  OF  THE  DIFFERENT  TYPES  IN  PRACTICE  116 

VIII.     IGNITING  ARRANGEMENTS 202 

IX.      ON    SOME   OTHER   MECHANICAL    DETAILS           .            .            .       .  226 

X.     THEORIES  OF  THE  ACTION  OF  THE  GASES  IN  THE  GAS 

ENGINE 243 

XL     THE  FUTURE  OF  THE  GAS  ENGINE 260 

PART    II. 

GAS  ENGINES  PRODUCED  SINCE   1886. 

\ 

I.     GAS  ENGINES  GIVING  AN  IMPULSE  FOR  EVERY  REVOLUTION^  271 

II.     OTTO  CYCLE  GAS  ENGINES 297 


xii  The  Gas  Engine 

CHAPTER  1>AGE 

III.  THE  PRODUCTION  OF  GAS  FOR  MOTIVE  POWER         .  .     354 

IV.  THE  PRESENT  POSITION  OF  GAS  ENGINE  ECONOMY  .     .     375 


PART    III. 
OIL  ENGINES. 

I.     PETROLEUM  AND  PARAFFIN  OILS        .  ...     387 

II.     OIL  ENGINES  ....  4°7 

III.     THE  DIFFICULTIES  OF  OIL  ENGINES  ...  .     462 

APPENDIX   I. 

AUIABATIC  AND  ISOTHERMAL  COMPRESSION  OF  DRY  AlR  .        .    .    475 
VARIOUS  ANALYSES  OF  COAL  GAS 476 

APPENDIX   II. 

COMPOSITION  OF  COAL  AND  CANNEL  GASES  (FRANKLAND)     .         .     478 
DATA  CALCULATED  FROM  FRANKLAND'S  ANALYSIS     .        .        .     .     479 

OXYGEN  REQUIRED   FOR   COMPLETE   COMBUSTION   OF   THE  GASES 
GIVEN  IN  FRANKLAND'S  ANALYSIS 480 

LIST  OF  BRITISH  GAS  AND  OIL  ENGINE  PATENTS  FROM   1791  TO 
1893  INCLUSIVE 481 

NAME  INDEX  TO  GAS  AND  OIL  ENGINE  PATENTS.        .        .        .535 


GENERAL   INDEX    ..........     547 


THE 

GAS     ENGINE. 

HISTORICAL   SKETCH  OF  THE   GAS  ENGINE. 

THE  origin  of  the  gas  engine  is  but  imperfectly  known  ;  by  some 
it  is  dated  as  far  back  as  1680,  when  Huyghens  proposed  to  use 
gunpowder  for  obtaining  motive  power.  Papin,  in  1690,  continued 
Huyghens'  experiments,  but  without  success.  The  method  used 
was  a  fairly  practicable  one.  The  explosion  was  used  indirectly  ; 
a  small  quantity  of  gunpowder  exploded  in  a  large  cylindrical  vessel 
filled  with  air,  expelled  the  air  through  check  valves,  thus  leaving, 
after  cooling,  a  partial  vacuum.  The  pressure  of  the  atmosphere 
then  drove  a  piston  down  to  the  bottom  of  the  vessel,  lifting  a 
weight  or  doing  other  work. 

In  a  paper,  published  at  Leipsic  in  1688,  Papin  stated  that, 
'  until  now  all  experiments  have  been  unsuccessful ;  and  after  the 
combustion  of  the  exploded  powder,  there  always  remains  in  the 
cylinder  about  one-fifth  of  its  volume  of  air.' 

The  Abbe  Hautefeuille  made  similar  proposals,  but  does  not 
seem  to  have  made  actual  experiments.  These  early  engines 
cannot  be  classed  as  gas  engines.  The  explosion  of  gunpowder  is 
so  different  in  its  nature  from  that  of  a  gaseous  mixture  that  com- 
parison is  untenable.  The  first  real  gas  engine  described  in  this 
country  is  in  Robert  Street's  patent,  No.  1983,  1794.  It  contains  a 
motor  cylinder  in  which  works  a  piston  connected  to  a  lever, 
from  which  lever  a  pump  is  driven.  The  bottom  of  the  motor 
cylinder  is  heated  by  a  fire  ;  a  few  drops  of  spirits  of  turpentine 

B 


2  The  Gas  Engine 

being  introduced  and  evaporated  by  the  heat,  the  motor  piston 
is  drawn  up,  and  air  entering  mixes  with  the  inflammable  vapour, 
the  application  of  a  flame  to  a  touch-hole  causing  explosion  :  and 
the  piston  being  driven  up  forces  the  pump  piston  down,  so  per- 
forming work  in  raising  water.  The  details,  as  described,  are 
crude,  but  the  main  idea  is  correct  and  was  not  improved  upon  in 
practice  till  very  lately. 

Samuel  Brown's  inventions  come  next.     His  patents  are  dated 
1823  and  1826,  Nos.  4874  and  5350.     The  principle  used  is  in- 


A,  Cover  raised,  vessel  filling  with  flame.  B  and  C,  Covers  down,  vessels  vacuous. 

FIG.  i. — Brown's  Gas-vacuum  Engine,  1826. 

genious,  and  easily  carried  out  in  practice,  but  it  is  not  economical, 
and  it  gives  a  very  cumbrous  machine  for  the  amount  of  power 
produced.  A  partial  vacuum  is  produced  by  filling  a  vessel  with 
flame,  and  expelling  the  air  it  contains,  a  jet  of  water  is  thrown 
in  and  condenses  the  flame,  giving  vacuum.  The  atmospheric 
pressure  thus  made  available  for  power  is  utilised  in  any  engine  of 
ordinary  construction. 

Brown's  apparatus  consists  essentially  of  a  large  upright  cylin- 


Historical  Sketch  of  the  Gas  Engine  3 

drical  vessel  fitted  on  the  top  with  a  movable  valve  cover,  of  the 
whole  diameter  of  the  cylinder.  The  cover  is  raised  and  lowered 
from  and  to  its  seat  by  a  lever  and  suitable  gear  at  proper  times. 
The  gas  supply  pipe  enters  the  cylinder  at  the  bottom  ;  the 
cylinder  being  filled  with  air,  and  the  valve  raised,  the  gas 
cock  is  opened  and  the  issuing,  gas  lighted  by  a  small  flame 
as  it  enters  the  cylinder.  The  flame  produced  fills  the  whole 
vessel,  expelling  the  air  it  contains  ;  the  valve  being  now 
lowered  and  the  gas  supply  shut  off,  the  water-jet  is  thrown  in 
and  causes  condensation.  To  keep  up  a  constant  supply  of  power, 
several  of  these  cylinders  are  required,  so  that  one  at  least  may  be 
always  vacuous  while  the  others  are  in  the  process  of  obtaining 
the  vacuum.  In  the  specification  three  are  shown  and  three 
engines.  The  engines  are  all  connected  to  the  same  crank-shaft. 
Notwithstanding  this  :  provision,  the  motion  must  have  been 
irregular.  The  idea  was  evidently  suggested  by  the  condensing 
steam  engine  ;  instead  of  using  steam  to  obtain  a  vacuum  flame  is 
employed.  Brown's  engine,  although  uninteresting  theoretically, 
is  important  as  being  the  first  gas  engine  undoubtedly  at  work. 
According  to  the  '  Mechanics'  Magazine,'  published  in  London,  a 
boat  was  fitted  with  one  including  a  complete  gas  generating 
plant,  and  was  run  upon  the  Thames  not  for  public  use  but  only 
as  an  experiment.  Another  engine  was  made  in  combination 
with  a  road  carriage  ;  it  also  ran  in  London.  \  If  these  statements 
are  to  be  relied  upon,  then  Samuel  Brown  was  a  really  great  man 
and  should  be  considered  as  the  Newcomen  of  the  gas  engine  ;  in 
some  points  he  achieved  a  measure  of  success  not  yet  equalled  by 
his  successors. 

W.  L.  Wright,  1833,  No.  6525. — In  this  specification  the 
drawings  are  very  complete  and  the  details  are  carefully  worked 
out.  The  explosion  of  a  mixture  of  inflammable  gas  and  air  acts 
directly  upon  the  piston,  which  acts  through  a  connecting  rod  upon 
a  crank-shaft.  The  engine  is  double-acting,  the  piston  receiving 
two  impulses  for  every  revolution  of  the  crank-shaft.  In  appear- 
ance it  resembles  a  high  pressure  steam  engine  of  the  kind  known 
as  the  table  pattern.  The  gas  and  air  are  supplied  to  the  motor 
cylinder  from  separate  pumps  through  two  reservoirs,  at  a  pressure 
a  few  pounds  above  atmosphere,  the  gases  (gas  and  air)  enter 

B  2 


4  The  Gas  Engine 

spherical  spaces  at  the  ends  of  the  motor  cylinder,  partly  displacing 
the  previous  contents,  and  are  ignited  while  the  piston  is  crossing 
the  dead  centre.  The  explosion  pushes  the  piston  up  or  down 
through  its  whole  stroke  ;  at  the  end  of  the  stroke  the  exhaust 
valve  opens  and  the  products  of  combustion  are  discharged  during 


FIG.  2. — Wright's  Gas-exploding  Engine,  1833. 

the  return,  excepting  the  portion  remaining  in  the  spaces  not 
entered  by  the  piston.  The  ignition  is  managed  by  an  external 
flame  and  touch-hole.  The  author  has  been  unable  to  find 
whether  the  engine  was  ever  made,  but  the  knowledge  of  the 
detail  essential  to  a  working  gas  engine  shown  by  the  drawings 
indicates  that  it  or  some  similar  machine  had  been  worked  by  the 


Historical  Sketch  of  the  Gas  Engine  5 

inventor.  Both  cylinder  and  piston  are  water-jacketed,  as  would 
have  been  necessary  in  a  double-acting  gas  engine  to  preserve  the 
working  parts  from  damage  from  the  intense  heat  of  the  explosion. 
This  is  the  earliest  drawing  in  which  this  detail  is  properly  shown. 
William  Barnett,  1838,  No.  7615. — Barnett's  inventions  as 
described  in  his  specification  are  so  important  that  they  require 
more  complete  description  than  has  been  here  accorded  to  earlier 
inventors. 

Barnett  is  the  inventor  of  a  very  good  form  of  igniting  arrange- 
ment. The  flame  method  most  widely  used  at  the  present  time 
was  originated  by  him. 

Barnett  is  also  the  inventor  of  the  compression  system  now  so 
largely  used  in  gas  engines.  The  Frenchman,  Lebon,  it  is  true, 
described  an  engine  using  compression,  in  the  year  1801,  but  his 
cycle  is  not  in  any  way  similar  to  that  proposed  by  Barnett,  or 
used  in  the  modern  gas  engine.  Barnett  describes  three  engines. 
The  first  is  single-acting,  the  second  and  third  are  double-acting  ; 
all  compress  the  explosive  mixture  before  igniting  it.  In  the  first 
and  second  engines  the  inflammable  gas  and  air  is  compressed  by 
pumps  into  receivers  separate  from  the  motor  cylinder,  but  com- 
municating with'  it  by  a  short  port  which  is  controlled  by  a  piston 
valve.  The  piston  valve  also  serves  to  open  communication 
between  the  cylinder  and  the  air  when  the  motor  piston  dis- 
charges the  exhaust  gases. 

In  the  third  engine  the  explosive  mixture  is  introduced  into 
the  motor  cylinder  by  pumps,  displacing  as  it  enters  the  exhaust 
gases  resulting  from  the  previous  explosion  ;  the  motor  piston  by 
its  ascent  or  descent  compresses  the  mixture.  Part  of  the  com- 
pression is  accomplished  by  the  charging  pumps,  but  it  is  always 
completed  in  the  motor  cylinder  itself. 

In  all  three  engines  the  ignition  takes  place  when  the  crank  is 
crossing  the  dead  centre,  so  that  the  piston  gets  the  .impulse  during 
the  whole  forward  stroke. 

Fig.  3  is  a  sectional  elevation  of  the  first  engine,  showing  the 
principal  working  parts,  but  omitting  all  detail  not  required  for 
explaining  the  action. 

There  are  three  cylinders  containing  pistons  ;  A  is  the  motor 
piston,  B  is  the  air  pump  piston.  The  gas  pump  piston  cannot  be 


6  The  Gas  Engine 

seen  in  the  section,  but  works  in  the  same  crosshead  as  B.  The 
motor  piston  is  suitably  connected  to  the  crank  shaft,  and  the 
other  two  are  also  connected  by  levers  in  such  manner  that  all 
three  move  simultaneously  up  or  down.  The  pump  pistons, 
moving  up,  take  respectively  air  and  inflammable  gas  into  their 


JIG.  3.— Barnett  Gas  Engine. 

cylinders  ;  upon  the  down  stroke  the  gases  are  forced  through  an 
automatic  lift  valve  into  the  receiver  D,  and  there  mix.  When  the 
down  stroke  is  complete  and  the  receiver  is  fully  charged  with  the 
explosive  mixture,  the  pressure  has  risen  to  about  25  Ibs.  per  square 
inch  above  atmosphere.  At  the  same  time  as  the  pumps  are  com- 
pressing, the  motor  piston  is  moving  down  and  discharging  the 


Historical  Sketch  of  tJie  Gas  Engine  7 

exhaust  gases  from  the  power  cylinder:  it  reaches  the  bottom  of 
its  stroke  just  when  compression  is  complete.  The  piston  valve 
E  then  opens  communication  between  the  receiver  and  the  motor, 
at  the  same  time  closing  to  atmosphere.  The  motor  cylinder 
being  in  free  communication  with  the  receiver,  the  explosion  of 
the  mixture  is  accomplished  by  the  igniting  cock  or  valve  F  ;  the 
pressure  resulting  actuates  the  motor  piston  during  its  whole  up- 


FIG,  4!  —  Barnett's  Igniting  Cock. 

ward  stroke,  the  hot  gases  flowing  through  the  port  o  precisely  as 
steam  would  do.  The  volume  of  the  receiver  being  constant,  the 
pressure  in  the  motor  cylinder  slowly  falls  by  expansion,  due  to 
the  movement  of  the  piston,  upon  which  work  is  performed,  and 
by  cooling,  the  pressure  still  existing  in  the  cylinder  when  the 
stroke  is  complete  depending  on  the  ratio  between  the  volume 
swept  by  the  motor  piston  and  the  volume  of  the  receiver. 


8  The  Gas  Engine 

The  down  stroke  again  expels  the  products  of  combustion,  the 
valve  opening  to  atmosphere,  while  the  compression  again  takes 
place.  This  cycle  gives  a  single-acting  engine.  It  is  obvious  that  as 
the  piston  A  does  not  enter  the  receiver  it  cannot  displace  the 
exhaust  gases  there.  If  means  are  not  taken  to  expel  these  gases 
they  must  mix  with  the  fresh  explosive  charge  pumped  in. 

It  is  very  desirable  that  these  gases  should  be  as  completely 
as  possible  discharged.  An  exhausting  pump  is  described  for 
doing  this,  but  in  small  engines  it  adds  an  additional  complication  ; 
and  so  Barnett  states  that  in  some  cases  it  may  be  omitted.  The 
exhaust  gases  do  not  so  injuriously  affect  the  action  of  small  gas 
engines. 

The  igniting  valve  is  very  ingenious.  It  is  shown  at  Fig.  4,  on  a 
larger  scale.  A  hollow  conical  plug  A  is  accurately  ground  into 
the  shell  B,  and  is  kept  in  position  by  the  gland  c  ;  the  shell  has 
two  long  slits  D  and  E  ;  the  plug  has  one  port  so  cut  that  as  the 
plug  moves  it  shuts  to  the  slit  D  before  opening  to  E.  In  the 
bottom  of  the  shell  there  is  screwed  a  cover  carrying  a  gas  burner 
F,  which  may  be  lit  while  the  port  in  the  plug  is  open  to  the  air 
through  D.  The  external  constant  flame  H  lights  it.  So  long 
as  the  plug  remains  in  this  position  the  internal  flame  continues 
to  bum  quietly.  If  the  plug  be  now  turned  to  shut  to  the  outer 
air,  it  opens  to  the  slit  E,  and  as  that  contains  explosive  mixture 
it  at  once  ignites.  The  explosion  extinguishes  the  internal  flame, 
but  it  is  again  lighted  at  the  proper  time  when  the  plug  is  moved 
round.  The  valve  acts  well  and  is  almost  identical  in  principle 
with  the  flame-igniting  arrangements  of  Hugon,  Otto  and  Langen 
and  Otto. 

Barnett's  second  engine  is  identical  with  his  first  except  that 
it  is  double-acting,  and  therefore  requires  a  greater  number  of 
parts. 

Barnett's  third  engine  is  worthy  of  careful  description.  Fig.  5 
is  a  vertical  section  of  the  principal  parts.  It  is  double-acting. 
It  has  three  cylinders,  motor,  air-pump  and  gas-pump  ;  the  air 
and  gas  pumps  are  single-acting,  the  motor  piston  is  double- 
acting.  The  pumps  are  driven  from  a  separate  shaft,  which  is 
actuated  from  the  main  crank  shaft  by  toothed  wheels  ;  the  wheel 
upon  the  pump  shaft  is  half  the  diameter  of  that  on  the  motor 


Historical  SketcJi  of  the  Gas  Engine  9 

shaft,  so  that  it  makes  two  revolutions  for  one  of  the  other.  The 
pumps  therefore  make  one  up-and-down  stroke  for  each  up  or 
down  stroke  of  the  motor  piston  ;  the  angles  of  the  cranks  are  so 
set  that  they  (pumps)  discharge  their  contents  into  one  or  other  side 
of  the  motor  cylinder  at  every  stroke-;  the  exhaust  gases  are  partly 


FIG.  5. — Barnett  Engine. 

displaced  by  the  fresh  explosive  mixture,  and  the  motor  piston  com- 
pletes the  compression  in  the  motor  cylinder  itself.  When  full  up 
or  down  the  igniting  cock  acts,  and  the  explosion  drives  the  piston 
to  the  middle  of  its  stroke  ;  it  here  runs  over  a  port  in  the  middle 
of  the  cylinder,  and  the  pressure  at  once  falls  to  atmosphere. 


IO  The  Gas  Engine 

A  is  the  motor  piston  ;  B  is  the  air-pump  piston  ;  c  is  the  gas- 
pump  piston,  which  is  behind  the  air-pump,  and  therefore  not 
seen  in  the  section  ;  D  is  the  main  crank  shaft ;  E  the  pump  shaft 
driven  from  the  main  shaft  by  the  wheels  F  and  G.  The  engine 
is  exceedingly  interesting  as  the  first  in  which  the  compression  is 
accomplished  in  the  motor  cylinder,  but  it  is  not  so  good  a  machine 
as  the  first  because  of  the  difficulty  of  obtaining  a  sufficient  amount 
of  expansion. 

From  1838  to  1854  inclusive  eleven  British  patents  were  applied 
for  ;  some  were  not  completed  but  only  reached  the  provisional 
stage.  Of  these  patents  by  far  the  most  important  is  Barnett's  ;  the 
others  are  interesting  as  showing  the  gradual  increase  of  attention 
the  subject  attracted.  The  other  names  are  Ador,  1838  ;  Johnson, 
1841  ;  Robinson,  1843  ;  Reynolds,  1844  ;  Brown,  1846  ;  Roger, 
1853,  also  Bolton  and  Webb,  making  three  patents  for  the  year  ; 
for  1854  two  patents,  Edington  and  Barsanti  and  Matteucci.  None 
of  the  proposals  in  these  patents  are  really  valuable  or  novel, 
being  anticipated  by  either  Street,  Wright,  or  Samuel  Brown. 
Robinson's  is  the  best,  being  similar  to  Lenoir's  in  some  of  its 
details,  and  showing  distinctly  a  better  understanding  of  gas 
engine  detail. 

A.  V.  Newton,  1855,  No.  562. — This  specification  is  interesting, 
and  describes  for  the  first  time  a  form  of  igniting  arrangement 
only  now  coming  into  use  ;  it  seems  to  be  identical  with  the 
invention  of  the  American  Drake,  although  not  described  as  a 
communication  from  him.  It  is  a  double-acting  engine,  and  takes 
into  the  cylinder  a  charge  of  gas  and  air  mixed,  during  a  portion 
of  the  stroke,  at  atmospheric  pressure.  The  igniting  arrangement 
is  a  thimble-shaped  piece  of  hard  cast-iron  which  projects  into  a 
recess  formed  in  the  side  of  the  cylinder ;  it  is  hollow,  and  is  kept 
at  all  times  red-hot  by  a  blow-pipe  flame  projected  into  it  by  a  small 
pump.  When  the  piston  uncovers  the  recess  the  explosive  gases 
coming  in  contact  with  it  ignite,  and  the  pressure  produced  drives 
it  forward. 

This  is  the  first  instance  of  ignition  by  contact  with  red-hot 
metal ;  the  proposal  has  often  been  made  since  then  in  varying 
forms. 

Barsanti  and  Matteucci,  1857,  No.  1655.— This  is  the  first  free 


Historical  Sketch  of  the  Gas  Engine  \  i 

piston  engine  ever  proposed ;  instead  of  allowing  the  explosion  to  act 
>directly  upon  the  motive  power  shaft  through  a  connecting  rod, 
at  the  moment  of  explosion  the  piston  is  perfectly  free.  The 
cylinder  is  very  long,  and  is  placed  vertically.  When  the  explosion 
occurs,  it  expends  its  power  in  giving  the  piston  velocity  ;  the 
expansion  therefore  takes  place  with  considerable  rapidity,  and 
the  piston,  gaining  speed  until  the  pressure  upon  it  falls  to  atmo- 
sphere, moves  on,  till  the  energy  of  motion  is  absorbed  doing  work 
on  the  external  air,  lifting  the  piston  and  in  friction.  When  the 
energy  is  all  absorbed  in  this  manner  it  stops  ;  it  has  reached  the 
top  of  its  stroke.  A  partial  vacuum  has  been  formed  in  the  cylinder, 
and  the  weight  has  been  raised  through  the  stroke.  It  now 
returns  under  the  pressure  of  the  atmosphere  and  its  own  weight ; 
in  returning,  a  rack  attached  to  the  piston  engages  the  motive  shaft 
and  drives  it.  The  cooling  of  the  gases  as  the  piston  descends 
continues  and  helps  to  keep  up  the  vacuum. 

The  method  although  indirect  is  economical.  Three  advantages 
are  gained  by  it — rapid  expansion,  considerable  expansion  (an  ex- 
pansion of  six  times  is  common  in  these  engines),  and  also  some 
of  the  advantages  of  a  condenser. 

Fig.  6  shows  a  vertical  section  of  their  best  modification.  The 
motor  piston  A  working  in  the  tall  vertical  cylinder  B  is  attached  to 
the  rack  c,  which  works  into  the  toothed  wheel  D.  The  motor 
shaft  E  revolves  in  the  direction  of  the  arrow,  and  it  is  provided 
with  a  ratchet ;  a  pall  upon  the  wheel  D  engages  the  ratchet  on  the 
down  stroke  of  the  piston  only,  on  the  up  stroke  it  slips  freely 
past  the  ratchet.  The  piston  A  is  therefore  quite  free  to  move 
without  the  shaft  on  the  up  stroke,  but  it  engages  on  the  down 
stroke.  The  cams  F  and  G  are  arranged  to  strike  projections 
upon  the  rack,  and  so  raise  or  lower  the  piston.  It  is  raised  when 
the  charge  is  to  be  taken  in,  and  lowered  when  it  has  completed 
its  working  stroke  and  the  exhaust  gases  have  to  be  discharged. 
When  raised  the  valve  H  is  in  the  position  shown.  Air  first  enters 
the  cylinder  through  the  port  i,  which  also  serves  to  discharge  the 
exhaust.  After  the  piston  has  uncovered  the  port  K  the  valve  H 
shuts  on  i,  opening  at  the  same  time  on  K  ;  the  gas  supply  then 
enters  and  mixes  more  or  less  perfectly  with  the  air  previously 
introduced. 


12 


The  Gas  Engine 


A  small  further  movement  of  the  piston  now  closes  the  valve, 
and  the  explosion  is  caused  by  the  passage  of  the  electric  spark  in 
the  position  indicated  upon  the  drawing.  The  piston  shoots  up 


FIG.  6. — Barsanti  and  Matteucci  Engine,  1857. 

freely  to  the  top  of  its  stroke,  to  give  out  the  work  stored  up  usefully 
upon  its  return. 

As  the  next  engine  to  be  described  marks  the  beginning  of  the 


Historical  Sketch  of  the  Gas  Engine  1 3 

practicable  stage  of  gas  engine  development,  it  is  advisable  to 
summarise  before  proceeding. 

Previous  to  1860  the  gas  engine  was  entirely  in  the  experimental 
stage:  Many  attempts  were  made,  but  none  of  the  inventors 
sufficiently  overcame  the  practical  difficulties  to  make  any  of  their 
engines  commercially  successful.  This  was  mostly  due  to  the 
very  serious  nature  of  the  difficulties  themselves,  but  it  was  also 
due  to  too  great  ambition  of  the  inventors  ;  they  wished  not  only 
to  compete  with  the  steam  engine  for  small  powers,  but  for  large 
powers.  They  thought  in  fact  more  to  displace  the  steam  engine 
than  to  compete  with  it. 

This  is  clearly  shown  in  many  of  their  descriptions  of  the  appli- 
cations of  their  inventions. 

The  greatest  credit  is  due  to  Wright  and  Barnett.  Wright 
very  closely  proposed  the  modern  non-compression  system,  Barnett 
the  modern  compression  system.  Barnett  is  also  the  originator  of 
one  of  the  modern  flame  systems  for  ignition.  Barsanti  and 
Matteucci  follow  in  order  of  merit  as  the  inventors  of  the  free-piston 
gas  engine. 

M.  .Lenoir  occupies  the  honourable  position  of  the  inventor 
of  the  first  gas  engine  ever  actually  introduced  to  public  use.  The 
engine  was  not  strikingly  novel ;  nothing  was  done  in  it  which  had 
not  been  proposed  before,  but  its  details  were  thoroughly  and 
carefully  worked  out.  It  was  in  fact  the  first  to  emerge  from  the 
purely  experimental  stage.  Lenoir's  real  credit  consists  in  over- 
coming .  the  practical  difficulties  sufficiently  to  make  previous 
proposals  fairly  workable. 

The  principle  is  exceedingly  simple  and  evident.  The  piston 
moves  forward  for  a  portion  of  its  stroke,  by  the  energy  stored  in 
the  fly  wheel,  and  takes  into  the  cylinder  a  charge  of  gas  and  air 
at  the  ordinary  atmospheric  pressure.  The  valves  cut  off  com- 
munication, and  the  explosion  is.  occasioned  by  the  electric  spark  ; 
this  propels  the  piston  to  the  end  of  the  stroke.  Exhausting  is 
done  precisely  as  in  the  steam  engine. 

The  engine  is  simply  an  ordinary  high-pressure  steam  engine  with 
valves  arranged  to  admit  gas  and  air  and  discharge  the  products 
of  combustion.  Fig.  7  is  an  external  elevation  of  a  three-horse 
engine.  It  was  first  constructed  in  Paris  in  1860  by  M.  Hippolyte 


The  Gas  Engine 


Historical  Sketch  of  the  Gas  Engine  1 5 

Marinoni.  In  Moigno's  '  Cosmos '  of  that  year  it  is  stated  that  two 
engines  were  in  course  of  manufacture,  one  of  six"  horse -power,  the 
other  of  twenty.  -  j£/ 

The  early  statements  of  its  economy  were  ludicrously  inaccurate. 
A  one  horse-power  engine  consumed,  it  was  said,  but  3  cubic  metres 
(106  cubic  ft.  nearly)  of  coal  gas  in  twelve  hours'  work,  and  therefore 
cost  for  fuej.  not  more  than  one-half  of  what  a  steam  engine  would 
have  done. 

The  actual  consumption  was  speedily  shown  to  be  much  nearer 
3  cubic  metres  per  effective  horse-power  per  hour. 

Notwithstanding  the  high  consumption,  the  engine  had  many 
good  points  ;  its  action  was  exceedingly  smooth  ;  no  shock  whatever 
was  heard  from  the  explosion.  Indeed  it  is  quite  impossible  when 
watching  the  engine  in  motion  to  realise  that  regular  explosions 
are  occurring.  The  motion  is  as  smooth  and  silent  as  in  the  best 
steam  engines. 

In  the  'Practical  Mechanics'  Journal'  of  August  1865,  there 
is  an  article  describing  the  progress  made  by  the  engine  since  the 
date  of  its  introduction,  from  which  it  appears  that  in  Paris  and 
France  from  300  to  400  engines  were  then  at  work,  the  power  ranging 
from  half  horse  to  three  horse. 

The  Reading  Iron  Works  Company,  Limited,  at  Reading,  un- 
dertook the  manufacture  for  this  country.  One  hundred  engines 
were  made  and  delivered  by  them  :  several  of  them  have  continued 
at  work  till  now.  Notably  one  engine  inspected  by  the  author  at 
Petworth  House,  Petworth,  worked  for  twenty  years  pumping  water, 
and  is  even  yet  in  good  condition. 

The  work  performed  by  the  engines  was  multifarious  in  its 
character— printing,  pumping  water,  driving  lathes,  cutting  chaff, 
sawing  stone,  polishing  marble,  in  fact,  wherever  from  one-half  to 
three  horse-power  was  sufficient. 

Lenoir's  patent  in  this  country  was  obtained  by  J.  H.  Johnson, 

1860,  No.  335.     It   describes  very  closely  the  engine  as  manu- 
factured both  in  France  and  England.     The  subsequent  patent, 

1 86 1,  No.  107,  does  not  seem  to  have  been  carried  into  effect. 
These  specifications  contain  many  erroneous  ideas,  showing 

the  notions  then  prevalent  among  inventors  of  the  nature  of 
gaseous  explosions.  Lenoir  erroneously  supposed  that  the  economy 


1 6  The  Gas  Engine 

of  his  engine  would  be  improved  if  he  could  obtain  a  slower 
explosion.  He  evidently  thought  that  the  power  imparted  to  the 
piston  by  explosion  was  similar  in  nature  to  a  sudden  blow — a 
rapid  rise  of  pressure,  and  a  fall  nearly  as  rapid.  He  therefore 
attempted  to  avoid  explosion  by  such  expedients  as  stratification 
and  injection  of  steam  or  water  spray.  The  stratification  idea  he 
very  clearly  expressed  in  his  second  specification,  stating  that  *  the 
object  of  preventing  the  admixture  of  air  and  gas  is  to  avoid 
explosion.'  It  is  somewhat  extraordinary  to  find  notions  so 
erroneous  common  at  a  time  when  Bunsen's  work  had  clearly 
proved  the  continuous  nature  of  the  combustion  in  gaseous  explo- 
sions, and  when  Hirn  had  made  experiments  which  showed  that 
the  heat  evolved  by  explosion  in  a  gas  engine  was  only  a  small 
part  of  the  total  heat  of  the  combustion,  the  heat  which  did  not 
appear  during  explosion  being  produced  during  expansion. 

Other  speculations  on  the  cause  of  the  uneconomical  working 
of  the  engine  were  frequent,  but  the  true  reason  was  fully  explained 
by  Gustav  Schmidt  in  a  paper  read  before  '  The  Society  of  Ger- 
man Engineers '  in  1861.  He  states  :  'The  results  would  be  far 
more  favourable  if  compression  pumps,  worked  from  the  engine, 
compressed  the  cold  air  and  cold  gas  to  three  atmospheres  before 
entrance  into  the  cylinder  ;  by  this  a  greater  expansion  and  trans- 
formation of  heat  is  possible.' 

This  opinion  became  common  at  this  time.  Compression 
engines  were  proposed  with  great  clearness  and  a  full  understand- 
ing of  the  advantages  to  be  gained. 

Million,  1861,  No.  1840. — This  Frenchman  had  exceedingly 
clear  ideas  of  the  advantages  of  compression  ;  he  evidently  con- 
siders himself  as  the  first  to  propose  its  use  in  a  gas  engine, 
apparently  unaware  of  the  existence  of  Barnett's  engine  already 
described.  He  claims  the  exclusive  right  to  use  compression  in 
the  most  emphatic  language. 

The  first  engine  described  is  exactly  what  Schmidt  asks  for. 
Separate  pumps  compress  the  air  and  gas  into  a  reservoir,  from 
which  the  movement  of  the  motor  piston,  during  a  portion  of  the 
stroke,  withdraws  its  charge  under  compression.  Ignition  is  ac- 
complished by  the  electric  spark,  and  the  piston  moves  forward 
under  the  high  pressure  produced.  He  states  : 


Historical  Sketch  of  the  Gas  Engine  \j 

'  In  ordinary  air  engines  the  operation  of  the  motive  cylmdersr 
is  analogous  to  that  of  the  pumps,  the  result  being  that  there  are 
two  cylinders,  -which  act  in  directions  contrary  to  each  other,  and 
that  the  pump,  which  is  an  organ  of  resistance,  even  works  at  a 
greater  pressure  than  that  of  the  motive  cylinder,  which  is  an 
organ  of  power.  Thus  these  engines  are  very  large  in  proportion  to 
their  power.  On  the  contrary  by  employing  gases  under  the  con- 
ditions above  explained,  these  engines  will  exert  great  power  in 
proportion  to  their  dimensions.  The  sudden  ignition  of  the  gases 
in  the  motive  cylinder  causes  the  latter  to  work  at  an  operative 
pressure  much  greater  than  that  of  the  pumps.' 

The  advantage  of  compression  in  a  ga>  engine  could  not  be 
more  fully  and  clearly  stated.  But  he  goes  even  a  step  further ; 
he  sees  that  the  portion  of  the  motor  piston  stroke  spent  in  taking 
in  the  charge  under  compression,  is  a  disadvantage,  and  he  pro- 
poses to  make  the  whole  stroke  available  for  power  by  providing  a 
space  at  the  end  of  the  cylinder  in  which  the  gases  are  compressed. 

'Instead  of  introducing  the  cold  gases  into  the  cylinders, 
during  a  portion  of  the  stroke  and  igniting  them  afterwards,  when 
the  induction  ceases  .  .  .  another  arrangement  might  be  adopted. 
The  motive  cylinder  might  be  made  longer  than  necessary,  in 
order  that  the  piston  should  always  leave  between  it  and  the  end 
of  the  cylinder  a  greater  or  less  space,  according  to  the  pleasure 
of  the  constructor,  such  as  one-fourth  or  one-third,  more  or  less, 
of  the  volume  generated  by  the  motive  piston.  This  space  is 
called  by  the  inventor  a  cartridge.  On  opening  the  slide  valve 
the  gases  could  be  allowed  to  enter  suddenly  from  the  pressure 
reservoir  into  this  cartridge  towards  the  dead  point,  and  this  induc- 
tion having  ceased,  an  electric  spark  would  ignite  the  gases  in 
the  cartridge  by  which  the  driving  piston  would  be  set  in  motion.' 

Such  an  engine  would  resemble  in  its  action  the  best  modern 
compression  engines.  The  difficulties  of  ignition  however  are  too 
considerable  to  be  overcome  without  further  detail. 

The  compression  idea  at  this  date  was  evidently  widely 
spread,  because  it  again  crops  up  in  a  remarkably  clever  pamphlet 
by  M.  Alph.  Beau  de  Rochas,  published  at  Paris  in  1862.  He 
advances  a  step  further  than  Million,  and  investigates  the  con- 
ditions of  greatest  economy  in  gas  engines  using  compression, 

c 


1 8  The  Gas  Engine 

with  reference  to  volume  of  hot  gases  and  surfaces  exposed.  He 
states  that  to  obtain  economy  with  an  explosion  engine,  four  con- 
ditions are  requisite  : 

1.  The  greatest  possible  cylinder  volume  with  the  least  pos- 
sible cooling  surface. 

2.  The  greatest  possible  rapidity  of  expansion. 

3.  The  greatest  possible  expansion  ;  and 

4.  The  greatest  possible  pressure  at  the  commencement  of  the 
expansion. 

In  using  boiler  tubes,  he  states,  the  efficiency  of  the  heat 
transmitted  increases  with  reduction  in  the  diameter  of  the  tubes. 
In  the  case  of  engine  cylinders,  therefore,  the  loss  of  heat  of  explo- 
sion would  be  in  inverse  ratio  to  the  diameter  of  the  cylinders. 

Therefore,  he  reasons,  an  arrangement  which  for  a  given  con- 
sumption of  gas,  gives  cylinders  of  the  greatest  diameters,  will 
give  the  best  economy,  or  least  loss  of  heat  to  the  cylinder.  One 
cylinder  only  must  be  employed  in  such  an  engine. 

But  loss  of  heat  depends  also  upon  time  ;  cooling,  therefore, 
will  be  proportionately  greater  as  the  working  speed  is  slower. 

The  sole  arrangement  capable  of  combining  these  conditions,  he 
states,  consists  in  using  the  largest  possible  cylinder,  and  reducing 
the  resistance  of  the  gases  to  a  minimum.  This  leads,  he  states, 
to  the  following  series  of  operations. 

1.  Suction  during  an  entire  outstroke  of  the  piston. 

2.  Compression  during  the  following  instroke. 

3.  Ignition  at  the  dead  point  and  expansion  during  the  third 
stroke. 

4.  Forcing  out  of  the  burned  gases  from  the  cylinder  on  the 
fourth  and  last  return  stroke. 

The  ignition  he  proposes  to  accomplish  by  the  increase  of 
temperature  due  to  compression.  This  he  expects  to  do  by 
compressing  to  one- fourth  of  the  original  volume. 

In  our  own  country  the  late  Sir  C.  W.  Siemens  proposed  com- 
pression in  1862.  The  idea  was  exceedingly  widely  spread,  as  is 
evident  from  those  numerous  and  independent  inventions.  The 
practical  experience  to  enable  it  to  be  successfully  effected  had 
yet  to  be  created,  however,  and  this  took  many  years  of  patient 
work. 


Historical  Sketch  of  the  Gas  Engine  19 

The  igniting  arrangement  was  the  first  weak  point  requiring 
improvement.  The  electrical  method  of  Lenoir  was  exceedingly 
delicate  and  troublesome. 


C2 


2Q  The  Gas  Engine 

Hugon's  engine,  produced  in  1865,  was  similar  to  Lenoir's  ; 
but  the  igniting  was  accomplished  by  flame,  a  modification  of 
Barnett's,  1838,  using  a  slide  valve  instead  of  a  lighting  cock. 
The  flame  ignition  was  certain  and  easily  kept  in  order.  In 
other  points  the  engine  was  a  great  improvement  upon  its  prede- 
cessor. The  lubrication  was  improved  by  injecting  water  into  the 
cylinder  and  the  cooling  water  jacket  was  better  arranged.  As  a 
result  the  consumption  of  gas  was  reduced. 

Fig.  8  is  an  external  elevation  of  the  Hugon  engine. 
Air.  Otto  now  appears  upon  the  scene.  Before  him  much  had 
been  done  in  inventing  and  studying  engines,  but  it  remained  for 
him  by  sheer  perseverance  and  determination  of  character,  to 
overcome  all  difficulties  and  reduce  to  successful  practice  the 
theories  of  his  predecessors. 

In  1867  Messrs.  Otto  and  Langen  exhibited  at  the  Paris  exhibi- 
tion of  that  year,  their  free  piston  engine,  exterior  elevation  shown 
at  fig.  9.  It  was  absolutely  identical  in  principle  with  the  previous 
invention  of  Barsanti  and  Matteucci,  but  the  details  were  com- 
pletely and  successfully  carried  out.  The  Germans  succeeded 
commercially  and  scientifically  when  the  Italians  completely 
failed. 

Flame  ignition  was  used  and  great  economy  was  obtained,  a  half- 
horse  engine,  according  to  Professor  Tresca,  giving  over  half-horse 
power  effective,  on  a  gas  consumption  at  the  rate  of  44  cubic  feet 
per  effective  horse-power  per  hour.  This  is  less  than  half  the 
consumption  of  Lenoir  or  Hugon  ;  accordingly  the  prejudice  ex- 
cited by  the  strange  appearance  and  noisy  action  of  the  engine 
did  not  prevent  its  sale  in  large  numbers.  It  completely  crushed 
Lenoir  and  Hugon,  and  held  almost  sole  command  of  the  market 
for  ten  years,  several  thousands  being  constructed  in  that  period. 

The  Bray  ton  gas  engine  appeared  in  America  in  1873,  but 
although  more  mechanical  than  any  free  piston  engine,  its  economy 
was  insufficient  to  enable  it  to  compete.  It  was  better  than  Lenoir 
or  Hugon,  but  not  nearly  so  good  as  Otto  and  Langen. 

Other  inventors  attempted  free  piston  engines,  but  with  small 
success. 

In  1876  Mr.  Otto  superseded  his  former  invention  by  the 
production  of  the  *  Otto  Silent '  engine,  now  known  all  over  the 


Historical  Sketch  of  the  Gas  Engine  ,2J 

globe.  It  is  a  compression  engine,  using  the  precise  cycle  described 
in  1862  by  Beau  de  Rochas,  but  carried  out  in  a  most  perfect 
manner  and  using  a  good  form  of  flame  ignition,  a  modified  Otto  and 
Langen  valve  in  fact.  The  economy  is  greater  than  that  of  any 


FIG.  9.— Otto  and  Langen  Free  Piston  Engine. 

previous  engine,  one  indicated  horse  being  obtained  upon  20  cubic 
feet  of  gas,  or  one  effective  horse  upon  24  to  30  cubic  feet  pei 
hour. 

This  engine  has  established  gas  engines  upon  a  firm  commercial 
basis,  15,000  having  been  sold  since  its  invention  ;  this  represents 
at  least  an  effective  power  of  90,000  horses. 


22  The  Gas  Engine 

Strangely  enough,  although  Mr.  Otto  is  the  greatest  and  most 
successful  gas  engine  inventor  who  has  yet  appeared,  he  adheres 
to  Lenoir's  erroneous  ideas,  and  in  his  specification  2081  of  1876 
he  attributes  the  economy  of  his  machine  to  a  slow  explosion  caused 
by  arrangement  of  gases  within  the  cylinder. 

The  compression,  which  is  the  real  cause  of  the  economy  and 
efficiency  of  the  machine,  he  seems  to  consider  as  an  accidental  and 
unessential  feature  of  his  invention. 

The  gas  engine,  like  all  great  inventions,  is  the  result  of  the 
long-continued  labour  of  many  minds  ;  it  is  a  gradual  growth  due 
to  the  united  labours  of  many  inventors.  In  the  earlier  days  of 
motive  power,  explosion  was  as  much  in  the  minds  of  the  inventors, 
Huyghens  and  Papin,  as  steam,  but  the  mechanical  difficulties 
proved  too  great.  The  constructive  skill  of  the  time  was  heavily 
taxed  by  the  rude  steam  engine  of  Newcomen,  and  still  more 
unequal  to  the  invention  of  James  Watt  ;  it  was  in  1774  that  Watt 
ran  his  first  successful  steam  engine  at  Soho  Works,  Birmingham. 
Twenty  years  later,  1794,  Street's  gas  engine  patent  indicated  the 
direction  of  men's  minds,  seeking  a  rival  for  steam  before  steam  had 
been  completely  introduced.  The  experience  and  skill  accumulating 
in  the  construction  of  the  steam  engine  made  the  gas  engine  more 
and  more  possible. 

The  proposals  of  Brown,  1823  ;  Wright,  1833  ;  Barnett,  1838  ; 
Barsanti  and  Matteucci,  1857,  show  gradually  increasing  knowledge 
of  detail  and  the  difficulties  to  be  overcome,  all  leading  to  the  first 
practicable  engine  in  1860,  the  Lenoir. 

Since  that  date  till  now,  twenty-five  years,  great  advances  have 
been  made,  and  at  present  the  gas  engine  is  the  only  real  rival  to 
steam. 


CHAPTER  I. 

THE    GAS    ENGINE   METHOD. 

GAS  ENGINES,  while  differing  widely  in  theory  of  action  and 
mechanical  construction,  possess  one  feature  in  common  which 
distinguishes  them  from  other  heat  engines  :  that  feature  is  the 
method  of  heating  the  working  fluid. 

The  working  fluid  is  atmospheric  air,  and  the  fuel  required  to 
heat  it  is  inflammable  gas.  In  all  gas  engines  yet  produced,  the 
air  and  gas  are  mixed  intimately  with  each  other  before  introduc- 
tion to  the  motive  cylinder  ;  that  is,  the  working  fluid  and  the 
fuel  to  supply  it  with  heat  are  mixed  with  each  other  before  the 
combustion  of  the  fuel. 

The  fuel,  which,  in  the  steam  and  in  most  hot-air  engines,  is 
burned  in  a  separate  furnace,  is,  in  the  gas  engine,  introduced 
directly  to  the  motive  cylinder  and  burned  there.  It  is  indeed 
part  of  the  working  fluid. 

This  method  of  heating  may  be  called  the  gas-engine  method, 
and  from  it  arises  at  once  the  great  advantages  and  also  the  great 
difficulties  of  these  motors. 

Compare  first  with  the  steam  engine.  In  it  there  exist  two 
great  causes  of  loss  :  water  is  converted  into  steam,  absorbing  a 
great  amount  of  heat  in  passing  from  the  liquid  to  the  gaseous 
state  ;  after  it  has  been  used  in  the  engine  it  is  rejected  into  the 
atmosphere  or  the  condenser,  still  existing  as  steam.  The  heat 
necessary  to  convert  it  from  the  liquid  to  the  gas  is  consequently 
in  most  part  rejected  with  it.  Loss,  occurring  in  this  way,  would 
be  small  if  high  temperatures  could  be  used  ;  but  this  is  the  point 
where  steam  fails.  High  temperatures  cannot  be  obtained  without 
pressure  so  great  as  to  be  quite  unmanageable.  The  attempt  to  obtain 
high  temperatures  by  super-heating  has  often  been  made,  but  with- 


24  The  Gas-  Engine 

out  any  substantial  success.  Although  the  difficulty  of  excessive 
pressure  is  avoided,  another  set  of  troubles  are  introduced.  All  the 
heat  to  be  given  to  the  gaseous  steam  must  pass  through  the  iron 
plates  forming  the  boiler  or  super-heater,  which  plates  will  only 
stand  a  comparatively  low  temperature,  certainly  not  exceed- 
ing that  of  a  low  red  heat,  or  about  600°  to  700°  C.  Steam, 
being  a  gas,  is  much  more  difficult  to  heat  than  water  ;  it  follows 
that  even  these  temperatures  cannot  be  attained  without  enormous 
addition  to  the  heating  surface.  The  difficulties  of  making  a 
workable  engine  using  high  temperature  steam  are  so  great  that 
even  so  distinguished  an  engineer  and  physicist  as  the  late  Sir 
C.  W.  Siemens  failed  in  his  attempts,  which  extended  over  many 
years.  It  may  be  taken  then  that  low  temperature  is  the  natural 
and  unavoidable  accompaniment  of  the  steam  method,  arising 
from  the  necessary  change  of  the  physical  state  of  the  working 
fluid,  and  the  limited  temperature  which  iron  will  safely  bear. 
The  originators  of  the  science  of  thermodynamics  have  long 
taught  that  the  maximum  efficiency  of  a  heat  engine  is  obtained 
when  there  is  the  maximum  difference  between  the  highest  and 
lowest  temperatures  of  the  working  fluid.  So  long  ago  as  1854, 
Professor  Rankine  read  a  paper  before  the  British  Association, 
'  On  the  means  of  realising  the  advantages  of  the  Air  Engine,'  in 
which  he  expresses  his  belief  that  such  engines  will  be  found  to  be 
the  most  economical  means  of  developing  motive  power  by  the 
agency  of  heat.  In  this  opinion  he  stood  by  no  means  alone. 
Engineers  so  able  as  Stirling,  Ericsson,  and  Siemens  ;  physicists 
so  distinguished  as  Dr.  Joule,  and  Sir  Wm.  Thomson,  devoted 
much  energy  and  study  to  their  practice  and  theory.  Notwith- 
standing all  their  efforts,  aided  by  a  host  of  less  able  inventors, 
the  difficulties  proved  too  formidable  ;  and  although  more  than 
thirty  years  have  now  passed  since  Rankine  announced  his  belief, 
the  hot-air  engine  proper,  has  made  no  real  advance.  Similar 
causes  to  those  acting  in  the  steam  engine  impose  a  limit  here. 
It  is  true  the  complication  of  changing  physical  state  is  avoided, 
but  the  limited  resistance  of  iron  to  heat  acts  as  powerfully 
as  ever.  Air  is  much  more  difficult  to  heat  than  water,  and,  there^ 
fore,  requires  a  much  larger  surface  per  unit  of  heat  absorbed. 
In  the  larger  hot-air  engines,  accordingly,  the  furnaces  and  heating 


The  Gas  Engine  MetJiod  2$ 

surfaces  gave  great  trouble.  Very  low  maximum  temperatures 
were  attained  in  practice.  In  a  Stirling  engine  giving  out  thirty- 
seven  brake  horse-power,  the  maximum  temperature  was  only 
343°  C.  ;  in  the  engines  of  the  ship  '  Ericsson/  the  maximum  was 
only  about  212°  C.,  according  to  Rankine,  the  indicated  power 
being  about  300  horses.  These  figures  show  that  the  heating 
surfaces  were  insufficient,  as  in  both  cases  the  furnaces  were  pushed 
to  heat  the  metal  to  a  good  red.  A  method  of  internal  firing  was 
proposed,  first  by  Sir  George  Cayley  and  afterwards  carried  out 
with  some  success  by  others  ;  the  furnace  was  contained  in  a 
completely  closed  vessel,  and  the  air  to  be  heated  was  forced 
through  it  before  passing  to  the  motor  cylinder.  The  plan  gave 
better  results,  but  the  temperature  of  700°  C.  was  still  the  limit,  as 
the  strength  of  the  iron  reservoir  had  to  be  considered,  and  the 
hot  gases  had  to  pass  through  valves.  Wenham's  engine,  described 
in  a  paper  read  before  the  Institution  of  Mechanical  Engineers  in 
1873,  is  a  good  example  of  this  class.  In  it  the  highest  temperature 
of  the  working  fluid,  as  measured  by  a  pyrometer,  was  608°  C. ; 
higher  temperatures  could  easily  have  been  got  but  the  safety  of 
the  engine  did  not  permit  it.  Professor  Rankine  in  his  work  on 
the  steam  engine  has  very  fully  discussed  the  disadvantages  arising 
from  low  maximum  temperatures.  He  calculates  that  in  a  perfect 
air  engine  without  regenerator  an  average  pressure  of  8-3  Ibs. 
per  square  inch  would  only  be  attained  with  a  maximum  of 
216 '6  Ibs.  per  square  inch,  thus  necessitating  great  strength  of 
cylinder  and  working  parts  ior  a  very  small  return  in  effective 
power.  In  the  '  Ericsson,'  the  average  effective  pressure  was  less 
than  this,  being  only  about  2  Ibs.  per  square  inch ;  it  had  four  air 
cylinders  each  of  14  feet  diameter,  and  only  indicated  300  horse- 
power. Stirling's  motor  cylinder  did  not  give  a  true  idea  of  the 
bulk  of  the  engine,  as  the  real  air-displacer  was  separate.  Even 
with  Wenham's  machine  the  bulk  was  excessive,  an  engine  of 
24  inches  diameter  cylinder  and  12  inches  stroke  giving  4  horse- 
power. 

Those  facts  sufficiently  illustrate  the  practical  difficulties  which 
prevented  the  development  of  the  hot-air  engine  proper.  All  flow 
from  the  method  of  heating.  Low  temperature  is  necessary  to 
secure  durability  of  the  iron. 


26  The  Gas  Engine 

All  hot-air  engines  are,  therefore,  very  large  and  very  heavy 
for  the  power  they  are  capable  of  exerting. 

The  friction  of  the  parts  is  so  great  that  although  the  theoreti- 
cal efficiency  of  the  working  fluid  is  higher  than  in  the  best  steam 
engines,  the  practical  efficiency  or  result  per  horse  available  for 
external  work  is  not  nearly  so  great.  The  best  result  ever  claimed 
for  Stirling's  engine  is  27  Ibs.  of  coal  per  bk.  horse-power  per 
hour,  probably  under  the  truth,  but  even  allowing  it,  a  first  class 
steam  engine  of  to-day  will  do  much  better.  According  to  Prof. 
Norton,  the  engines  of  the  '  Ericsson  '  used  1*87  Ibs.  of  anthracite 
per  indicated  horse-power  per  hour  ;  but  the  friction  must  have  been 
enormous.  Compared  with  the  steam  engine,  the  practical  disadvan- 
tages of  the  hot-air  engine  are  much  greater  than  its  advantage  of 
theory.  Owing  to  the  great  inferiority  of  air  to  boiling  water  as  a 
medium  for  the  convection  of  heat,  the  efficiency  of  the  furnace  is 
much  lower  ;  owing  to  the  high  maximum  and  low  available  pres- 
sure, the  friction  is  much  greater  — which  disadvantages  in  practice 
more  than  extinguish  the  higher  theoretical  efficiency. 

The  gas  engine  method  of  heating  by  combustion  or  explosion 
at  once  disposes  of  those  troubles  ;  it  not  only  widens  the  limits 
of  the  temperatures  at  command  almost  indefinitely,  but  the  causes 
of  failure  with  the  old  method  become  the  very  causes  of  success 
with  the  new  method. 

The  difficulty  of  heating  even  the  greatest  masses  of  air  is 
quite  abolished.  The  rapidly  moving  flash  of  chemical  action 
makes  it  easy  to  heat  any  mass,  however  great,  in  a  minute  fraction 
of  a  second  ;  when  once  heated  the  comparatively  gradual  con- 
vection makes  the  cooling  a  very  slow  matter.  The  conductivity 
of  air  for  heat  is  but  slight,  and  both  losing  and  receiving  heat 
from  enclosing  walls  are  carried  on  by  the  process  of  convection, 
the  larger  the  mass  of  air  the  smaller  the  cooling  surface  relatively. 
Therefore  the  larger  the  volumes  of  air  used,  the  more  economical 
the  new  method,  the  more  difficult  the  old.  The  low  conductivity 
for  heat,  the  cause  of  great  trouble  in  hot-air  machines,  becomes 
the  unexpected  cause  of  economy  in  gas  engines.  If  air  were  a 
rapid  carrier  of  heat,  cold  cylinder  gas  engines  would  be  impos- 
sible. The  loss  to  the  sides  of  the  enclosing  cylinders  would  be 
so  great  that  but  little  useful  effect  <x>uld  be  obtained.  Even  as 


The  Gas  Engine  MetJwd  27 

it  is,  present  loss  from  this  cause  is  sufficiently  heavy.  In  the 
earlier  engines  as  much  as  three-fourths  of  the  whole  heat  of  the 
combustion  was  lost  in  this  way ;  in  the  best  modern  engines  so 
much  as  one-half  is  still  lost. 

A  little  consideration  of  what  is  occurring  in  the  gas  engine 
cylinder  at  each  explosion  will  show  that  this  is  not  surprising. 
Platinum,  the  most  infusible  of  metals,  melts  at  about  1700°  C; 
the  ordinary  temperature  of  cast  iron  flowing  from  a  cupola  is 
about  1200°  C.;  a  temperature  very  usual  in  a  gas  engine  cylinder 
is  1600°  C.,  a  dazzling  white-heat.  The  whole  of  the  gases  filling 
the  cylinder  are  at  this  high  temperature.  If  one  could  see  the 
interior  it  would  appear  to  be  filled  with  a  blinding  glare  of  light. 
This  experiment  the  writer  has  tried  by  means  of  a  small  aperture 
covered  with  a  heavy  glass  plate,  carefully  protected  from  the 
heat  of  the  explosion  by  a  long  cold  tube.  On  looking  through 
this  window  while  the  engine  is  at  work,  a  continuous  glare  of 
white  light  is  observed.  A  look  into  the  interior  of  a  boiler 
furnace  gives  a  good  notion  of  the  flame  filling  the  cylinder  of 
a  gas  engine. 

At  first  sight  it  seems  strange  that  such  temperature  can  be 
used  with  impunity  in  a  working  cylinder  ;  here  the  convenience 
of  the  method  becomes  evident.  The  heating  being  quite  inde- 
pendent of  the  temperature  of  the  walls  of  the  cylinder,  by  the  use 
of  a  water-jacket  they  can  be  kept  at  any  desired  temperature. 
The  same  property  of  rapid  convection  of  heat,  so  useful  for 
generating  steam  from  water,  is  essential  in  the  gas  engine  to  keep 
the  rubbing  surfaces  at  a  reasonable  working  temperature.  In 
this  there  is  no  difficulty,  and  notwithstanding  the  high  tempera- 
ture of  the  gases,  the  metal  itself  never  exceeds  the  boiling  point 
of  water. 

So  good  a  result  cannot  of  course  be  obtained  without  careful 
proportioning  of  the  cooling  surfaces  for  the  amount  of  heat  to  be 
carried  away  ;  in  all  modern  engines  this  is  carefully  attended  to, 
with  the  gratifying  result  that  the  cylinders  take  and  retain  a 
polished  surface  for  years  of  work  just  as  in  a  good  steam  engine. 

The  gas  engine  method  gives  the  advantage  of  higher  tempera- 
ture of  working  fluid  than  is  attainable  in  any  other  heat  engine, 
at  the  same  time  the  working  cylinder  metal  may  be  kept  as  cool 


28  The  Gas  Engine 

as  in  the  steam  engine.  It  also  allows  of  any  desired  rate  of  heat- 
ing the  working  fluid  in  any  required  volumes. 

In  consequence  of  high  temperatures  the  available  pressures 
are  high,  and  therefore  the  bulk  of  the  engine  is  small  for  the 
power  obtained. 

It  realises  all  the  thermodynamic  advantages  c'aimed  for  the 
hot-air  engine  without  sacrificing  the  high  available  pressures  and 
rapid  rate  of  the  generation  of  power  which  is  the  characteristic  of 
the  steam  engine. 

For  rapid  convection  of  heat  existing  in  the  s'eam  boiler  is 
substituted  the  still  more  rapid  heating  by  explosion  or  combustion, 
a  rapidity  so  superior  that  the  power  is  generated  for  each  stroke 
separately  as  required,  there  being  no  necessity  to  collect  a  great 
magazine  of  energy. 

The  only  item  to  the  debtor  side  of  the  gas  engine  account 
is  the  flow  of  heat  through  the  cylinder  walls,  which  disadvantage 
is  far  more  than  paid  for  by  the  advantages. 


CHAPTER   II. 

GAS    ENGINES    CLASSIFIED. 

ALTHOUGH  the  gas  engine  patents  now  in  existence  number  many 
hundreds,  the  essential  differences  between  the  inventions  are  not 
great.  In  their  working  process  they  may  be  divided  into  a  few 
well-defined  types  : 

1.  Engines  igniting  at  constant  volume,  but  without  previous 
compression. 

2.  Engines  igniting  at  constant  pressure,  with  previous  com- 
pression. 

3.  Engines  igniting  at  constant  volume,  with  previous  com- 
pression. 

THE  FIRST  TYPE  is  the  simplest  in  idea  ;  it  is  the  most  apparent 
method  of  obtaining  power  from  an  explosion. 

In  it  the  engine  draws  into  its  cylinder  gas  and  air  at  atmos- 
pheric pressure,  for  a  part  of  its  stroke,  in  proportions  suitable  for 
explosion  ;  then  a  valve  closes  the  cylinder,  and  the  mixture  is 
ignited.  The  pressure  produced  pushes  forward  the  piston  for 
the  remainder  of  its  travel,  and  upon  the  return  stroke  the  pro- 
ducts of  the  combustion  are  expelled  exactly  as  the  exhaust  of  a 
steam  engine.  By  repeating  the  same  process  on  the  other  side 
of  the  piston,  a  kind  of  double-acting  engine  is  obtained.  It  is 
not  truly  double-acting,  as  the  motive  impulse  is  not  applied 
during  the  whole  stroke,  but  only  during  that  portion  of  it  left 
free  after  performing  the  necessary  function  of  charging  with  the 
explosive  mixture. 

The  working  cycle  of  the  engine  consists  of  four  operations  : 

1.  Charging  the  cylinder  with  explosive  mixture. 

2.  Exploding  the  charge. 

3.  Expanding  after  explosion. 

4.  Expelling  the  burned  gases. 


30  The  Gas  Engine 

To  carry  it  out  in  a  perfect  manner,  the  mechanism  must  be 
so  arranged  that  during  the  charging,  the  pressure  of  the  gases  in 
the  cylinder  does  not  fall  below  atmosphere  ;  there  must  be  no 
throttling  of  the  entering  gases.  The  cut-off  and  the  explosion 
must  be  absolutely  simultaneous  and  also  instantaneous,  so  that 
the  heat  may  be  applied  without  change  of  volume,  and  thereby 
produce  the  highest  pressure  which  the  mixture  used  is  capable 
of  giving.  The  expansion  will  be  carried  fai  enough  to  reduce 
the  pressure  of  the  explosion  to  atmosphere  ;  and  the  exhaust 
stroke  will  be  accomplished  without  back  pressure.  The  charge 
in  entering  must  not  be  heated  by  the  walls  of  the  cylinder,  but 
should  remain  at  the  temperature  of  the  atmosphere  till  the  very 
moment  previous  to  ignition.  At  the  same  time,  the  cylinder 
should  not  cool  the  gases  after  the  explosion,  no  heat  should  dis- 
appear except  through  expansion  doing  work. 

Although  all  these  conditions  are  necessary  to  the  perfect 
cycle,  it  is  evident  that  no  actual  engine  is  capable  of  combining 
them.  Some  throttling  at  the  admission  of  the  mixture,  and  a 
little  back  pressure  during  the  exhausting  are  unavoidable  ;  some 
time  must  elapse  between  the  closing  of  the  inlet  valve  and  the 
explosion,  in  addition  to  the  time  taken  by  the  explosion  itself. 
Heat  will  be  communicated  to  the  entering  gases  and  lost  by  the 
exploded  gases  to  the  walls  of  the  cylinder. 

The  actual  diagram  taken  from  an  engine  will  therefore  differ 
considerably  from  the  theoretic  one. 

The  theoretical  conditions  are  to  a  great  extent  contradictory. 

The  idea  of  the  type,  however,  is  easily  comprehensible,  and 
evidently  suggested  by  the  common  knowledge  of  the  destructive 
effect  of  accidental  coal  gas  explosions  which  occurred  soon  after 
the  introduction  of  gas  into  general  use.  *  The  power  is  there,  let 
us  use  it  like  steam  in  the  cylinder  of  a  steam  engine,'  said  the 
early  inventors. 

The  two  most  successful  engines  of  this  type  were  Lenoir's 
and,  later,  Hugon's,  for  very  small  powers  ranging  from  one  man 
to  half-horse.  Simple  forms  of  this  type  are  still  in  extensive  use. 
The  most  widely  known  of  these  is  the  Bisschof,  a  French  inven- 
tion. 

THE  SECOND  TYPE  is  not  so  simple  in  its  main  idea,  and  required 


Gas  Engines  Classified  3 1 

much  greater  knowledge  of  detail,  both  mechanical  and  theoretical. 
As  a  hot-air  engine  its  theory  was  originally  proposed  by  Sir  Geo. 
Cayley,  and,  later,  by  Dr.  Joule  and  Sir  Wm.  Thomson.  As  a 
hot-air  engine  it  failed  for  the  reasons  discussed  in  the  previous 
chapter. 

In  it  the  engine  is  provided  with  two  cylinders  of  unequal 
capacity ;  the  smaller  serves  as  a  pump  for  receiving  the  charge 
and  compressing  it,  the  larger  is  the  motor  cylinder,  in  which  the 
charge  is  expanded  during  ignition  and  subsequent  to  it. 

The  pump  piston,  in  moving  forward,  takes  in  the  charge  at 
atmospheric  pressure,  in-  returning  compresses  it  into  an  inter- 
mediate receiver,  from  which  it  passes  into  the  motor  cylinder  in 
a  compressed  state.  A  contrivance  similar  to  the  wire  gauze  in  a 
Davy  lamp  commands  the  passage  between  the  receiver  and  the 
cylinder,  and  permits  the  mixture  to  be  ignited  on  the  cylinder 
side  as  it  flows  in  without  the  flame  passing  back  into  the 
receiver. 

The  motor  cylinder  thus  receives  its  working  fluid  in  the  state 
of  flame,  at  a  pressure  equal  to,  but  never  greater  than,  the 
pressure  of  compression.  At  the  proper  time,  the  valve  between 
the  motor  and  the  receiver  is  shut,  and  the  piston  expands  the 
ignited  gases  till  it  reaches  the  end  of  its  stroke,  when  the  exhaust 
valve  is  opened,  and  the  return  expels  the  burned  gases. 

The  ignition  here  does  not  increase  the  pressure,  but  increases 
the  volume.  The  pump,  say,  puts  one  volume  or  cubic  foot  into 
the  receiver  ;  the  flame  causes  it  to  expand  while  entering  the 
cylinder  to  two  cubic  feet.  It  does  the  work  of  two  cubic  feet  in 
the  motor  cylinder,  so  that,  though  there  is  no  increase  of  pres- 
sure, there  is  nevertheless  an  excess  of  power  over  that  spent  in 
compressing. 

In  the  first  type  of  engine  the  heat  is  given  to  the  working 
fluid  at  constant  volume,  in  the  second  type  the  heat  is  given  to 
the  working  fluid  at  constant  pressure  during  change  of  volume. 

The  working  cycle  of  the  engine  consists  of  five  operations  : 

1.  Charging  the  pump  cylinder  with  gas  and  air  mixture. 

2.  Compressing  the  charge  into  an  intermediate  receiver. 

3.  Admitting  the  charge  to  the  motor  cylinder  in  the  state  of 
flame,  at  the  pressure  of  compression. 


32  The  Gas  Engine 

4.  Expanding  after  admission. 

5.  Expelling  the  burned  gases. 

To  carry  out  the  process  perfectly  the  following  conditions 
would  be  required. 

No  throttling  during  admission  of  the  charge  to  the  pump. 

No  heating  of  the  charge  as  it  enters  the  pump  from  the 
atmosphere. 

No  loss  of  the  heat  of  compression  to  the  pump  and  receive! 
walls. 

No  throttling  as  the  charge  enters  the  motor  cylinder  from  the 
receiver. 

No  loss  of  heat  by  the  flame  to  the  sides  of  the  motor  cylinder 
and  piston. 

And  last,  No  back  pressure  during  the  exhaust  stroke. 

The  exhaust  gases  also  must  be  completely  expelled  by  the 
motor  piston  ;  that  is,  the  motor  cylinder  should  have  no  clear- 
ance. 

The  requirements  of  this  type,  although  sufficiently  numerous 
and  exacting,  are  not  so  contradictory  among  themselves  as  in  the 
first. 

Although  every  engine  of  the  kind  yet  made  fails  to  fulfil  them, 
it  is  quite  possible  that  a  machine  very  closely  approximating  may 
be  yet  constructed. 

The  most  successful  engines  of  this  kind  have  been  Brayton's 
and  Simon's,  the  first  an  American  invention,  and  the  second 
an  English  adaptation  of  it.  Sir  C.  W.  Siemens  proposed  such 
an  engine  in  1861,  but  does  not  seem  to  have  been  successful  in 
carrying  it  out.  In  1860  it  was  also  proposed  by  F.  Million,  but 
without  a  sufficient  understanding  of  the  mechanical  detail  neces- 
sary for  a  working  machine. 

Brayton's  engine  was  made  in  considerable  numbers  in  America, 
and  was  applied  by  him  to  drive  a  good-sized  launch,  petroleum 
being  used  as  the  fuel  instead  of  gas.  It  was  exhibited  at  the  Gen- 
tennial  Exhibition  in  Philadelphia  ;  at  the  Paris  exhibition  of  1878 
by  Simon. 

THE  THIRD  TYPE  is  the  best  kind  of  compression  engine  yet 
introduced  ;  by  far  the  largest  number  of  gas  engines  in  every  day 
use  throughout  the  world  are. made  in  accordance  with  its  require- 


Gas  Engines  Classified  33 

nients.  In  theory  it  is  more  easily  understood  as  requiring  two 
cylinders,  compression  and  power. 

The  leading  idea,  compression  and  ignition  at  constant  volume, 
was  first  proposed  by  Barnett  in  1838,  then  by  Schmidt  in  more 
general  terms,  very  fully  by  Beau  de  Rochas  in  1860  and  also  by 
F.  Million  in  the  same  year.  Otto,  however,  was  the  first  to  suc- 
cessfully apply  it,  which  he  did  in  1876. 

The  compression  cylinder  may  be  supposed  to  take  in  the 
charge  of  gas  and  air  at  atmospheric  temperature  and  pressure  ; 
compress  it  into  a  receiver  from  which  the  motor  cylinder  is  sup- 
plied ;  the  motor  piston  to  take  in  its  charge  from  the  reservoir  in 
a  compressed  state ;  and  then  communication  to  be  cut  off  and 
the  compressed  charge  ignited. 

Here  ignition  is  supposed  to  occur  at  constant  volume,  that  is, 
the  whole  volume  of  mixture  is  first  introduced  and  then  fired  ; 
the  pressure  therefore  increases.  The  power  is  obtained  by 
igniting  while  the  volume  remains  stationary  and  the  pressure  in-* 
creases. 

Under  the  pressure  so  produced,  the  piston  completes  its 
stroke,  and  upon  the  return  stroke  the  products  of  the  combus- 
tion are  expelled. 

In  this  case  the  working  cycle  of  the  engine  consists  of  six 
operations  : 

1.  Charging  the  pump  cylinder  with  gas  and  air  mixture. 

2.  Compressing  the  charge  into  an  intermediate  receiver. 

3.  Admitting  the   charge  to  the  motor  cylinder  under  com- 
pression. 

4.  Igniting  the  mixture  after  admission  to  the  motor. 

5.  Expanding  the  hot  gases  after  ignition. 

6.  Expelling  the  burned  gases. 

To  carry  out  the  process  perfectly,  similar  conditions  are  neces- 
sary to  those  in  the  second  type.  But  the  conditions  are  more 
contradictory.  The  gases  entering  the  cylinder  under  pressure  must 
not  be  heated  by  its  walls  ;  no  heat  should  be  added  till  the  igni- 
tion ;  then,  after  ignition  the  gases  must  not  lose  heat  to  the 
cylinder— conditions  which  it  is  impossible  for  the  same  cylinder 
to  fulfil  simultaneously. 

In  the  engines  constructed  the  receiver  is  dispensed  with,  for 

D 


34  The  Gas  Engine 

reasons  which  will  be  explained  in  discussing  the  practical  difficul- 
ties of  construction  ;  but  this  does  not  in  any  way  modify  the 
theory,  which  shall  first  be  discussed. 

The  most  considerably  used  engine  of  this  kind  is  the  Otto, 
next  to  it  coming  Clerk's  engine,  then  Robson's  by  the  Messrs. 
Tangye,  and  Andrews'  Stockport  compression  engine.  In  none 
of  these  types  does  any  part  of  the  working  cycle  require  either 
the  heating  or  the  cooling  of  the  working  fluid  by  the  relatively 
slow  processes  of  convection  and  conduction. 

Heating  is  accomplished  by  the  rapid  method  of  explosion  or, 
if  the  term  be  preferred,  combustion,  and  for  the  cooling  neces- 
sary in  all  heat  engines  is  substituted  the  complete  rejection  of 
the  working  fluid  with  the  heat  it  contains  and  its  replacement  by 
a  fresh  portion  taken  from  the  atmosphere  at  the  atmospheric 
temperature,  which  is  the  lower  limit  of  the  engines. 

This  is  the  reason  why  those  cycles  can  be  repeated  with 
almost  indefinite  rapidity,  and  why  gas  engines  can  be  run  at 
speeds  equal  to  steam  engines,  while  the  old  hot-air  engines  could 
not  be  run  fast,  because  of  the  very  slow  rate  at  which  air  could  be 
heated  and  cooled  by  contact. 

There  still  remains  one  important  type  of  gas  engine  not 
included  in  this  classification  ;  in  it  part  of  the  efficiency  is  de- 
pendent on  cooling  by  contact,  and  consequently  only  a  slow  rate 
of  working  stroke  can  be  obtained.  It  is  the  kind  of  engine 
known  as  the  free  piston  or  atmospheric  gas  engine.  It  may  be 
regarded  as  a  modification  of  the  first  type.  The  first  part  of  its 
action  is  precisely  similar,  the  latter  part  differs  considerably. 

It  may  be  called  Type  ONE  A.  In  it  the  piston  moves  for- 
ward, taking  in  its  charge  of  gas  and  air  from  the  atmosphere  at 
the  atmospheric  pressure  and  temperature.  When  cut  off  it  is 
ignited  instantaneously,  the  volume  being  constant  and  the 
pressure  increasing ;  the  piston  is  not  connected  directly  to  the 
motor  shaft,  but  is  free  to  move  under  the  pressure  of  the  explo- 
sion, like  the  ball  in  a  cannon.  It  is  shot  forward  in  the  cylinder 
(which  is  made  purposely  very  long)  ;  the  energy  of  the  explosion 
gives1  the  piston  velocity  ;  it  therefore  continues  to  move  con- 
siderably after  the  pressure  has  fallen  by  expansion  to  atmos- 
phere ;  a  partial  vacuum  forms  under  the  piston  till  its  whole 


Gas  Engines  Classified  35 

energy  of  motion  is  absorbed  in  doing  work  upon  the  exterior 
air.  It  then  stops,  and  the  external  pressure  causes  it  to  perform 
its  instroke,  during  which  a  clutch  arrangement  yokes  it  to  the 
motor  shaft,  giving  the  shaft  an  impulse.  The  explosion  is  made 
to  give  its  equivalent  in  work  upon  the  external  air,  in  forming  a 
vacuum  in  fact ;  the  vacuum  is  increased  by  the  cooling  of  the 
hot  gases  during  the  return  of  the  piston.  The  piston  proceeds 
completely  to  the  bottom  of  the  cylinder,  expelling  the  products 
of  combustion.  So  far  as  the  working  fluid  of  the  engine  is  con- 
cerned the  cycle  consists  of  five  operations  : 

1.  Charging  the  cylinder  with  explosive  mixture. 

2.  Exploding  the  charge. 

3.  Expanding  after  explosion. 

4.  Compressing  the  burned  gases  after  some  cooling. 

5.  Expelling  the  burned  gases. 

To  carry  it  out  perfectly,  in  addition  to  the  requirements  of  the 
first  type,  the  expansion  should  be  carried  far  enough  to  lower  the 
temperature  of  the  working  fluid  to  the  temperature  of  the  atmos- 
phere, and  the  compression  to  atmospheric  pressure  again  should 
be  conducted  at  that  temperature  ;  that  is,  the  compression  line 
should  be  an  isothermal. 

This  kind  of  engine  was  proposed  first  by  Barsanti  and  Mat- 
teucci  in  1854,  by  F.  H.  Wenham  in  1864,  and  then  by  Otto  and 
Langen  in  1866.  The  last  named  inventors  were  successful  in 
overcoming  the  practical  difficulties,  and  many  engines  were 
made  and  sold  by  them.  Their  engine,  although  cumbrous  and 
noisy,  was  a  good  and  economical  worker  ;  many  are  still  in  use. 
The  next  best  known  engine  of  the  kind  was  Gillies's,  of  which  a 
considerable  number  were  constructed  and  sold. 


The  Gas  Engine 


CHAPTER   III. 

THERMODYNAMICS    OF   THE   GAS    ENGINE. 

BEGINNING  with  Professor  Rankine,  able  writers  have  so  fully 
treated  the  thermodynamics  of  the  air  engine  that  but  little  can 
be  added  to  the  knowledge  of  the  subject  now  in  existence.  The 
gas  engine  method  of  heating,  however,  introduces  limits  of 
temperature  so  extended  and  cycles  of  action  so  different  from 
those  possible  in  the  air  engine  proper,  that  something  remains  to 
be  done  in  applying  the  existing  data.  So  far  as  the  author  is 
aware,  this  has  been  previously  attempted  by  three  writers  only — 
Prof.  R.  Schottler,  Dr.  A.  Witz,  and  himself. 

Before  proceeding  with  the  special  consideration  of  the  sub- 
ject, it  is  advisable  for  the  sake  of  completeness  to  state  briefly 
the  general  laws.  In  doing  so  Rankine  will  be  followed  as  closely 
as  possible. 

THERMODYNAMICS  DEFINED. 

'  It  is  a  matter  of  ordinary  observation  that  heat,  by  expanding 
bodies,  is  a  source  of  mechanical  energy,  and  conversely,  that 
mechanical  energy,  being  expended  either  in  compressing  bodies 
or  in  friction,  is  a  source  of  heat. 

*  The  reduction  of  the  laws  according  to  which  such  phenomena 
take  place  to  a  physical  theory  or  connected  system  of  principles 
constitutes  what  is  called  the  science  of  thermodynamics.' 

FIRST  LAW  OF  THERMODYNAMICS. 

Heat  and  mechanical  energy  are  mutually  convertible,  and 
heat  requires  for  its  production,  and  produces  by  its  disappear- 
ance, mechanical  energy  in  the  proportion  of  1,390  footpounds 
for  each  centigrade  heat  unit,  a  heat  unit  being  the  amount  of 


Thermodynamics  of  the  Gas  Engine  37 

heat  necessary  to  heat  one  pound  weight  of  water  through  i°  C. 
This  is  Joule's  law,  having  been  first  determined  by  him  in  1843. 
It  holds  with  equal  truth  for  other  forms  of  energy,  and  is  a 
general  statement  of  the  great  truth,  that  in  the  universe,  energy  is 
as  incapable  of  creation  or  destruction  as  matter.  Energy  may 
change  its  form  indefinitely  while  passing  from  a  higher  to  a 
lower  level,  but  it  can  neither  be  created  nor  destroyed.  The 
energy  of  outward  and  visible  movement  of  matter  may  be 
arrested  and  caused  to  disappear  as  movement  of  the  whole  mass 
in  one  direction,  but  its  equivalent  reappears  as  internal  move- 
ment or  agitation  of  the  particles  or  molecules  composing  the 
body.  Energy  assumes  many  forms,  but  the  sum  of  all  remains 
a  constant  quantity,  incapable  of  change  of  quantity,  but  capable 
of  disappearing  in  one  form  and  reappearing  in  another. 

v         '  "•' 
SECOND  LAW  OF  THERMODYNAMICS. 

Although  heat  and  work  are  mutually  convertible  and  in 
definite  and  invariable  proportions,  yet  no  conceivable  heat 
engine  is  able  to  convert  all  the  heat  given  to  it  into  work. 

Apart  altogether  from  practical  limitations,  a  certain  portion 
of  the  heat  must  be  passed  from  the  hot  body  to  the  cold  body  in 
order  that  the  remainder  may  assume  the  form  of  mechanical 
energy.  To  get  a  continuous  supply  of  mechanical  energy  from 
heat  depends  upon  getting  a  continuous  supply  of  hot  and  cold 
substances  :  it  is  by  the  alternate  expansion  and  contraction  of 
some  substance,  usually  steam  or  air,  that  heat  is  converted  into 
mechanical  energy. 

Perfect  heat  engines  are  ideal  conceptions  of  machines  which 
are  practically  impossible,  but  whose  operations  are  so  arranged 
that,  if  possible,  they  would  convert  the  greatest  conceivable 
proportion  of  the  heat  given  to  them  into  mechanical  work. 

Efficiency. — The  efficiency  of  a  heat  engine  is  the  ratio  of  the 
heat  converted  into  mechanical  work  to  the  total,  amount  of  heat 
which  enters  the  engine. 

In  this  work  the  word  Efficiency,  when  used  without  qualifica- 
tion, bears  this  meaning  only. 

The   efficiency  of  a   perfect  heat  engine  depends  upon  two 


3  3  The  Gas  Engine 

things  alone  :  these  are,  the  temperature  of  the  source  of  heat  and 
the  temperature  of  the  source  of  cold  (allowing  the  expression). 
The  greater  the  difference  between  these  temperatures  the  greater 
the  efficiency.  That  is,  the  greater  will  be  the  proportion  of  the 
total  heat  converted  into  mechanical  energy,  and  the  smaller  the 
proportion  of  the  total  heat  which  necessarily  passes  by  conduction 
from  the  hot  to  the  cold  body. 

Properties  of  Gases.— Gases  are  the  most  suitable  bodies  for 
use  in  heat  engines  ;  they  are  almost  perfectly  elastic,  and  they  ex- 
pand largely  under  the  influence  of  heat. 

A  gas  is  said  to  be  perfect  when  it  completely  obeys  two 

laws  : 

1.  Boyle's  law. 

2.  Charles's  law. 

Boyle's  Law. — Suppose  unit  volume  of  gas  to  be  contained  in 
a  cylinder  fitted  with  a  piston  which  is  perfectly  tight  at  unit 
pressure.  Suppose  the  temperature  to  be  kept  perfectly  constant. 
Then,  according  to  Boyle's  law,  however  the  volume  may  be 
changed  by  moving  the  piston,  the  pressure  is  always  inversely 
proportional  to  volume,  that  is,  if  volume  becomes  two,  pressure 
becomes  one-half;  volume  becomes  three,  pressure  becomes 
one-third. 

The  product  of  pressure  and  volume  is  always  constant. 

Denoting  pressure  by/,  and  volume  by  r>9 

Boyle's  law  is,  /  v  =  constant. 

Charleys  Law. — If  a  gas  kept  at  constant  volume  is  heated, 
the  pressure  increases.  If  a  gas  is  kept  behind  a  piston  which 
moves  without  friction  so  that  the  pressure  upon  the  gas  is  always 
constant,  the  heat  applied  will  cause  it  to  expand. 

One  volume  of  gas  at  o°  C,  if  heated  through  i°  C.  wfll  expand 
-2  J3>  and  become^  1^3-  volume,  if  the  pressure  fs  constant.  If  the 
volume  is  constant,  then  its  pressure  will  increase  by  ^f^,  that  is, 
its  pressure  will  become  i-gr-u  °f  tne  original.  In  the  same  way 
if  cooled  i°  C.  below  o°  C.,  it  will  contract  or  diminish  in  pressure 
by  ^j-^,  its  volume  or  pressure  becoming  f^f  of  what  it  is  at  o°  C~ 

For  every  degree  of  heat  or  cold  above  or  below  o°  C.  a  perfect 
gas  expands  or  contracts  by  ^  of  its  volume  at  o°  C. 


Thermodynamics  of  the  Gas  Engine  39 

.  From  this  it  is  evident  that  a  perfect  gas,  if  cooled  to  273°  C. 
below  o°  C.  will  have  neither  volume  nor  pressure. 

This  originally  gave  rise  to  the  conception  of  absolute  zero  of 
temperature.  The  absolute  temperature  of  a  body  is  ordinary 
temperature  Centigrade  +  273,  just  as  the  absolute  pressure  of  any 
gas  is  its  pressure  above  atmosphere  plus  atmospheric  pressure.  The 
absolute  temperature  of  a  body  is  its  temperature  above  Centigrade 
zero  +  273. 

The  pressure  or  volume  of  a  gas  is  therefore  directly  propor- 
tional to  its  absolute  temperature. 

If  /=pressure  for  absolute  temperature  /,  and  pl  pressure  for 
tl  temperature,  also  absolute, 

then        £_J,-          - 
or  if  v  be  the  volume  at  absolute  temperature  /  and  vl  at  tlt 


The  Second  Law  (quantitative}. — If  heat  be  supplied  to  a  perfect 
heat  engine  at  the  absolute  temperature  T1,  and  the  absolute  tem- 
perature of  the  source  of  cold  is  T,  then  the  efficiency  of  that 
engine  is,  denoting  it  by  E, 

rpl rp  rp 

E  =  —, .—  =  I   -   - . . 
T1  T1 

It  is  unity  minus  the  lower  temperature  divided  by  the  upper 

T* 

temperature.     The  efficiency  is  greater  or  less  as  the  fraction    — t 

is  less  or  greater.  This  fraction  may  be  diminished  either  by 
reducing  T  or  by  increasing  T1.  The  lowest  available  temperature 
is  not  capable  of  great  variation,  being  in  our  climate  about  290° 
absolute.  It  therefore  follows  that  efficiency  could  only  be  in- 
creased by  increasing  T1. 

Suppose  x=29o°  absolute  and  Tl=58o°  absolute. 

Then         E  =  i  —  f-|£  =  i  —  ^  =  0-5. 
Suppose  T=29o°,  and  T1  =  i45o°,  a  temperature  common  in 
gas  engines,  then 


40 


The  Gas  Engine 


The  efficiency  increases  with  increase  of  the  maximum  tempe- 
rature. The  second  law,  in  its  quantitative  form,  is  the  statement 
of  the  efficiency  of  any  perfect  heat  engine  in  terms  of  absolute 
temperatures  of  the  source  of  heat  and  the  source  of  cold. 

Thermal  Lines.— -If  &  volume  of  air  is  contained  in  a  cylinder 
having  a  piston  and  fitted  with  an  indicator,  the  piston,  if  moved 
to  and  fro,  will  alternately  compress  and  expand  the  air,  and  the 
indicator  pencil  will  trace  a  line  or  lines  upon  the  card,  which  lines 
register  the  change  of  pressure  and  volume  occurring  in  the  cylinder. 
If  the  piston  is  perfectly  free  from  leakage,  and  it  be  supposed  that 
the  temperature  of  the  air  is  kept  quite  constant,  then  the  line  so 
traced  is  called  an  Isothermal  line,  and  the  pressure  at  any  point 
when  multiplied  by  the  volume  is  a  constant  according  to  Boyle's 
law, 

pv  =  a  constant. 

If,  however,  the  piston  is  moved  in  very  rapidly,  the  air  will  not 
remain  at  constant  temperature,  but  the  temperature  will  increase 
because  work  has  been  done  upon  the  air,  and  the  heat  has  no 


8or 


sr   50 


I    £ 


H7_ 


Atmospheric  line 


6      10     20     30    40     50     60     70     80     90  loo 

VOLUME. 
Compression  lines  for  air  (dry),  Adiabatic  and  Isothermal. 

FlG.   10. 

time  to  escape  by  conduction.  If  no  heat  whatever  is  lost  by  any 
cause,  the  line  will  be  traced  over  and  over  again  by  the  indicator 
pencil,  the  cooling  by  expansion  doing  work  precisely  equalling 
the  heating  by  compression.  This  is  the  line  of  no  transmission 
of  heat,  therefore,  known  as  Adiabatic.  Fig.  10  shows  these  two 


Thermodynamics  of  the  Gas  Engine  4*' 

lines   for  air   starting  from  atmospheric  pressure  and   tempera- 
ture. 

The  pressures  at  different  points  of  the  curve  are  related  by  the 
equation 

pvy  —  constant. 

The  pressure  when  multiplied  by  the  volume  raised  to  the  y  power 
is  always-  constant. 

The  power  y  is  the  ratio  between  the  specific  heat  of  the  air  at 
constant  pressure  and  its  specific  heat  at  constant  volume.  Ac- 
cording to  Rankine 

y  =  i  '408  for  air. 

Imperfect  Heat  Engines. — For  a  complete  description  of  the 
working  cycle  of  perfect  heat  engines,  the  reader  is  referred  to 
works  upon  the  steam  engine,  which  contain  the  fullest  possible 
details  both  of  reasoning  and  results. 

The  working  cycles  of  practicable  heat  engines  are  always  im- 
perfect, that  is,  the  operations  are  such  that,  although  perfectly 
carried  out,  the  maximum  efficiency  possible  by  the  second  law  of 
thermodynamics  could  not  be  attained  by  them.  Each  cycle  has 
a  maximum  efficiency  peculiar  to  itself,  which  is  invariably  less 

than   ^    ~  T  ,  but  which  does  not  necessarily  vary  with  T1  and  T. 

It  does  not  always  follow  that  increase  of  the  higher  tempera- 
ture causes  increase  of  efficiency ;  conversely,  it  does  not  always 
follow  that  diminution  of  the  upper  temperature  causes  diminution 
of  efficiency.  Under  some  circumstances,  indeed,  the  opposite 
effect  is  produced— increase  of  the  upper  temperature  diminishes 
efficiency,  while  its  diminution  increases  it,  of  course  within  certain 
limits. 

All  the  gas  engine  cycles  described  in  the  previous  chapter  are 
imperfect  in  this  sense,  but  all  are  practicable.  It  follows  that  if 
any  one  of  them  gives  a  higher  efficiency  than  another  in  theory, 
it  will  also  do  so  in  practice,  provided  the  practical  losses  do  not  in- 
crease with  improved  theory. 

It  is  necessary  before  discussing  the  practical  losses  to  see  how 
the  cycles  compare  with  each  other,  if  each  be  perfectly  carried 
out.  The  results  obtained  can  then  be  modified  by  examination 
of  the  way  in  which  unavoidable  practical  losses  affect  each  cycle. 


42  The  Gas  Engine 


EFFICIENCY  FORMULA. 

If  H  is  the  quantity  of  heat  given  to  an  engine,  and  H1  the 
amount  of  heat  discharged  by  it  after  performing  work,  then,  the 
portion  which  has  disappeared  in  performing  work  is  H  —  H1, 
supposing  no  loss  of  heat  by  conduction  or  other  cause,  and  the 
efficiency  of  the  engine  is 

H  —  H1 

H 

Type  i. — A  perfect  indicator  diagram  of  an  engine  of  this  kind 
is  shown  at  fig.  1 1 :  the  line  a  b  c  is  the  atmospheric  line,  represent- 
ing 'volume  swept  by  the  piston,  the  line  a  d  is  the  line  of  pressures. 
From  a  to  b  the  piston  moves  forward,  taking  in  its  charge,  at 
atmospheric  temperature  and  pressure;  at  b  communication  is  in- 
stantaneously cut  off,  and  heat  instantaneously  supplied,  raising 
the  temperature  to  the  maximum,  before  the  movement  of  the  pis- 
ton has  time  to  change  the  volume.  From  e,  the  point  of  maxi- 
mum temperature  and  pressure,  the  gases  expand  without  loss  of 
heat,  the  temperature  only  falling  by  reason  of  work  performed 
till  the  pressure  again  reaches  atmosphere.  The  curve  e  c  is 
therefore  adiabatic.  In  all  cases  let 

/  be  the  initial  temperature  of  the  air  in  absolute  degrees  Centi- 
grade. 

T  the  absolute  temperature  after  explosion  or  heating. 

T  *  the  absolute  temperature  of  the  gases  after  adiabatic  ex- 
pansion. 

p  the  atmospheric  pressure. 

PO  the  absolute  pressure  of  the  explosion. 

v0  the  volume  at  atmospheric  temperature  and  pressure. 

v  the  volume  at  the  termination  of  adiabatic  expansion. 

In  the  particular  case  of  diagram  fig.  n,  where  the  expansion 
is  continued  to  the  atmospheric  line,  the  formula  expressing  the 
efficiency  is  very  simple.  Calling  KV  the  specific  heat  of  air  at 
constant  volume,  and  K,  the  sp.  heat  at  constant  pressure,  then 
the  heat  supplied  to  the  engine  is 


Thermodynamics  of  the  Gas  Engine 


43 


JJLLl 


d 

rt 

cu 

ss  <j  *»<i  v>     * 

I          s 

ri.t 

ft.  3-0 

|  =  =1    'u 
I  8 

rt  o  a  o  »      rt 


I    I   II   I  MC 


o 

0> 

9° 


=>! 


44  The  Gas  Engine 

and  the  heat  discharged  from  it  is 

H1  =  K/(T»-/) 

therefore  efficiency  is 


MT-/) 

and  ^l=y 

Kj, 

therefore          E  =  i  — 


It  is  evident  that  for  every  value  of  T  there  is  a  corresponding 
value  of  T1,  which  increases  with  the  increase  of  T.  If  TI  is 
known  in  terms  of  T,  then  the  calculation  of  efficiency  is  very 
rapid,  as  all  that  is  required  is  a  knowledge  of  the  maximum 
temperature  of  the  explosion  to  calculate  the  efficiency  of  an 
engine  using  that  maximum  temperature,  and  perfectly  fulfilling 
this  cycle. 

For  any  adiabatic  curve,  the  pressure  multiplied  by  volume 
which  has  been  raised  to  the  jyth  power  is  a  constant;  there- 
fore 

PO  ?'/  =p0vy  (see  diagram,  fig.  1 1),  \  (a) 

and  -  =  ^  whicH,  as  /  =  A,  is  the  same  as  -' ; 

*         P  Po 

also  *  =  ll. 

V*      * 

.*.  in  equation  (a)  T  may  be  substituted  for  P,,  t  for  /„  t  for  vm  and 

r'  for  vt  giving  , 


T'  =  /  {-Lj  i  •  (2) 

In  most  engines  of  this  type  the  expansion  is  not  great  enough 
to  reduce  the  pressure  to  atmosphere  before  opening  the  exhaust 
valve  ;  it  is  therefore  necessary  to  give  formulae  where  the  best 
condition  is  not  carried  out.  Fig.  12  is  a  diagram  of  a  case  of 
this  kind. 

The  pressure  at  the  termination  of  the  stroke  has  fallen  to  /„, 


Thermodynamics  of  the  Gas  Engine  45 

and  the  temperature  to  T1.     The  heat  supplied  to  the  engine  is 
the  same  as  in  the  first  case 


The  heat  discharged  by  it  cannot  be  so  simply  expressed. 
Suppose  the  hot  gases  at  the  pressure  p0  to  be  allowed  to  cool  by 
contact  with  the  sides  of  the  cylinder  at  constant  volume  till  the 
atmospheric  pressure  /  is  reached,  then  the  temperature 

tl   ~  T1  ^ 

A' 

or  in  terms  of  volume  and  /  tl  =  —  t, 

«  *"  0 

and  the  heat  lost  is  KV  (i1  —  /l ). 

The  heat  to  be  still  abstracted  before  the  air  returns  to  its 
original  condition  at  /,  and  pressure/  is 

M  >'-')• 

Total  heat  discharged  by  exhaust,  therefore, 


The  efficiency  consequently  is 
Kt,  (T  -/)-  { 


In  this  case  there  is  no  fixed  relationship  between  T  the  tempera- 
ture of  the  explosion,  and  T1  the  temperature  of  the  gases  at  the 
termination  of  adiabatic  expansion.  As  the  expansion  is  more  or 
less  complete,  so  does  T  and  xl  change.  In  no  case,  however, 
.can  the  efficiency  be  so  great  as  that  in  the  first  case. 

Type  2.  —  A  perfect  indicated  diagram  of  an  engine  of  this  type 
is  shown  at  fig.  13.  Although  the  cycle  requires  two  cylinders, 
producing  two  diagrams,  they  are  better  compared  when  super- 
posed. The  whole  diagram  may  be  supposed  to  come  from  the 
motor  cylinder,  the  shaded  portion  of  it  representing  the  available 
work  of  the  cycle,  and  the  unshaded  part,  the  part  done  by  the 
compressing  pump.  The  atmospheric  line  is  a  be.  The  pump 
volume  is  a  £,  the  motor  volume  is  a  c.  The  pump  takes  in  the 
volume  a  b  at  atmospheric  pressure  >  it  compresses  it  into  an 


46  The  Gas  Engine 

intermediate  receiver,  the  compression  line  (adiabatic)  is  bf, 
passing  into  receiver,  line  fe.  From  the  receiver  it  enters  the 
cylinder  at  the  constant  pressure  of  compression  on  the  line  efg, 
supply  of  heat  cut  off  at  g.  Then  expansion  (adiabatic)  to  the 
point  c  atmospheric  pressure.  The  part  bfgc  is  the  part  avail- 
able for  work,  the  part  bfea  representing  the  work  of  the  com^ 
pressing  pump,  which  is  deducted  from  the  total  motor  cylinder, 
diagram  aegc. 

The  total  volume  of  air  passed  through  the  pump  is  ?„  volume 
swept  by  motor  cylinder,  v.  So  far  as  the  heat  operations  are 
concerned,  the  part  of  the  diagram  to  volume  vc  may  be  disre- 
garded ;  it  represents  the  pressing  of  the  compressed  charge  into 
the  reservoir  after  reaching  the  maximum  pressure  of  compression 
(it  is  called  vc  because  it  is  volume  of  compression).  The  admis- 
sion to  the  motor  cylinder  is  identical,  so  that  work  done  in  pump 
in  that  part  equals  work  done  upon  the  motor  piston. 
In  addition  to  the  letters  used  in  type  i, 

vc  is  volume  of  compression. 

vp  volume  at  point  g  on  diagram. 

pc  is  pressure  of  compression. 

tc  is  temperature  of  compression. 

The  temperature,  volume,  and  pressure  letters  are  figured 
below  the  diagram  to  make  matters  clear.  Compression  is  carried 
on  from  volume  v0  at  atmospheric  pressure  and  temperature  to 
volume  vc  at  pressure  pe  and  temperature  "ta  the  curve  being 
adiabatic. 

After  compression,  heat  is  added  without  allowing  the  pres- 
sure to  increase,  but  the  piston  moves  out  till  the  maximum  tem- 
perature T  is  attained,  and  the  supply  of  heat  being  completely  cut 
off,  adiabatic  expansion  follows  till  the  atmospheric  pressure  is 
reached  ;  the  exhaust  valve  is  then  opened,  and  the  hot  gases  dis- 
charged. 

It  is  evident  that  as  the  pressure  is  constant,  while  heat  is 
being  given,  the  amount  of  heat  given  to  the  engine  in  all  is 

H  =  K>  (T  -  /,), 

and  the  heat  discharged  from  it  is  also  at  constant  pressure, 
H1  ,=  K,  (x1  -  /). 


Thermodynamics  of  the  Gas  Engine 


47 


•• 


>  3 

*    y  s  s 

d 


48  The  Gas  Engine 

The  efficiency  is  therefore 

V          /rp      /    \      K         /T  1       /  \ 

K^  (  L    —    lc)   —    K/  \  A  *  / 

E  ==  ~     7~i /\ 

rpl  / 

=  '  -  ^~  (4) 

The  compression  and  expansion  curves  being  adiabatic, 
Compression  pc  v*  =  p  v*, 
Expansion  pc  v/  =  p0vy\ 


and  *<^,  also?  =  -£ 

^         T  Z/         Tl 

Substituting  in  equation  (a) 


As  the  efficiency  is 


it  may  be  either  =  i  —  —  or  =  i  —  (5) 

T  tc 

That  is,  when  expansion  is  carried  to  the  same  pressure  as  existed 
before  compression,  the  efficiency  depends  upon  the  compression 
alone,  /  being  the  temperature  before  compression,  and  tc  the  tem- 

perature of  compression.     The  efficiency  being  i  —  -,  the  greater 

*<e 

the  temperature  tc  the  less  is  the  fraction  ~,  and  the  more  nearly 

tc 

does  E  approach  unity. 

In  most  working  engines  of  this  kind,  the  expansion  is  not 
continued  long  enough  to  make  the  pressure  after  expanding  fall 
to  atmosphere  ;  so  that  the  efficiency  is  never  so  great,  as  when  that 
is  done,  a  greater  portion  of  the  heat  is  discharged  than  need  be. 


Thermodynamics  of  the  Gas  Engine  49 

The  modification  of  the  formulae  is  precisely  as  in  type  i  for 
similar  circumstances.  A  diagram  of  the  kind  is  shown  at  fig.  14. 
The  temperature  tl  is  found  as  before  : 


- 

Po 

The  heat  supplied  to  the  cycle  is  as  before  : 

H  =  K,  (T  -  /,), 
and  the  heat  discharged  is 

H1  =  K.  (Tl   -  />)  +  K,  (/'   -  /). 

The  efficiency  is 

i  (Ti  _  ,.)  +  (f  _  t) 


Although  there  is  no  fixed  proportion  between  the  efficiency  and 
the  temperature  of  adiabatic  compression,  it  is  evident  that  E  in- 
creases with  increase  of  tc. 

Type  3.  —  A  perfect  indicator  diagram  of  an  engine  of  this  type 
is  shown  at  fig.  15.  As  in  type  2,  the  diagrams  of  pump  and 
motor  are  combined,  the  whole  diagram  being  that  given  in  the 
motor  cylinder,  but  the  shaded  portion  only  represents  the  avail- 
able work.  The  atmospheric  line  is  a  b  c.  The  pump  volume  is 
a  b,  the  motor  cylinder  volume  is  a  c.  The  pump  takes  in  the 
volume  a  b  at  atmospheric  pressure,  compresses  it  on  the  adiabatic 
line  bf  and  into  a  receiver  on  the  line/^.  The  compressed  gases 
enter  the  motor  cylinder  on  the  line^\/j  heat  is  added  instantane- 
ously, and  the  pressure  rises  on  the  line/*?.  Supply  of  heat  cut 
off  at  e  and  the  expansion  line  e  c  is  adiabatic.  The  total  diagram 
in  the  motor  cylinder  is  a  g  f  e  c,  but  the  portion  agfb  is 
common  to  motor  and  pump  ;  the  available  work  is  therefore 
bfec. 

The  total  volume  of  air  passed  through  the  pump  is  v0  ;  the 
volume  after  adiabatic  compression,  from  atmospheric  pressure  p 
and  temperature  /  to  pressure  of  compression  pc  and  temperature 
ta  is  vc  Heat  is  supplied  at  constant  volume  vc  till  the  maximum 
temperature  of  the  explosion  T  is  attained.  The  piston  then 
expands  the  hot  gases  adiabatically  from  temperature  T  to  T1 
and  pressure  PO  to  pressure  /„,  which  in  this  case  is  equal  to 
atmosphere. 

E 


t;o  The  Gas  Engine 

The  heat  is  discharged  in  passing  from  volume  v  to  v0  at  con- 
stant pressure  of  atmosphere.  The  part  of  the  diagram  from 
volume  vc  to  zero  may  be  disregarded  as  it  is  common  to  both 
pump  and  motor. 

The  heat  supplied  to  the  cycle  is 

H  =  K,  (T-/,). 


Thermodynamics  of  the  Gas  Engine  5  1 

Heat  discharged 

Hl  =  K^(T1-/). 

The  efficiency  is 


T  _  /x1 V 

7,~\7/  ' 


It  is  evident  that  for  any  maximum  temperature  T  and  com- 
pression temperature  tc  there  is  a  temperature  T1  at  which  the 
expansion  adiabatic  line  falls  to  atmosphere.  It  will  much  sim- 
plify subsequent  calculations  to  establish  the  relations  between  T, 
£,  /  and  T1. 

P^'/  =/X  and//,'/  =pv?  and  as  /,=/, 


but 


and  ?5  =  —  so  that 

A      ^ 

T1  in  terms  of  T,  tc  and  t  is  therefore 

(8) 

Although  this  is  the  best  case  for  the  third  type  it  is  not  the 
one  commonly  occurring  in  practice  ;  no  engine  has  as  yet  been 
arranged  to  expand  the  gases  after  explosion  to  the  atmospheric 
pressure. 

Fig.  1 6  is  a  perfect  diagram  of  the  most  common  case,  namely, 
when  the  expansion  is  carried  only  so  far  that  the  heat  is  dis- 
charged when  the  volume  is  the  same  as  that  existing  before  com- 
pression. The  formula  of  efficiency  is  exceedingly  simple,  and 
leads  to  a  very  apparent  and  nevertheless  somewhat  paradoxical 
result. 

The  heat  supplied  to  the  cycle  is 

H  =  KV  (T  -  /,), 
and  the  heat  discharged  is 

H1  =  KV  (x1  -  /), 

E2 


The  Gas  Engine 


because  the  volume  of  the  air  is  the  same  as  that  existing  before 
compression,  and  therefore  the  heat  necessary  to  bring  the  fluid 
back  to  its  original  state  can  be  abstracted  at  constant  volume. 

d  € 


i      '2     '3     '4      '5     "0      '7      '8      '9 


VOLUMES. 
t  absolute  temp.  CC.  at  b       p  absolute  pressure  at  b 


volume  at 


Here  Vo  =  v. 

FIG.   16. 
Type  3.     Perfect  diagram.     Expansion  to  same  vol.  as  before  compression. 


The  efficiency  is 


E  =  K,  (T  -  /,)  -  K,  (T1  -  /) 


i  — 


K.  (T  -  iy 

T1  -  / 


As  both  curves  are  adiabatic,  and  pass  through  the  same  volume 
change, 


Thermodynamics  of  the  Gas  Engine 


53 


so  that 


T    -  tc         T          te 

The  efficiency  may  therefore  be  expressed 
E  =  i  —  T-    or  i 

T  te 

[^  \y~ 
or 


(TO) 


That  is,  the  efficiency  depends  upon  the  ratio  between  the 
initial  temperature  and  the  temperature  of  adiabatic  compression 
only.  T,  the  temperature  of  explosion,  may  be  any  value  greater 
than  ta  without  either  increasing  or  diminishing  the  efficiency. 
In  this  case 


There  is  still  another  case  of  this  type  of  cycle  to  be  con- 
sidered, when  the  expansion  is  continued  beyond  the  original 
volume  before  compression,  but  not  carried  far  enough  to  reach 
atmospheric  pressure.  Fig.  17  is  a  diagram  of  the  kind. 

The  heat  supplied  to  the  cycle  is  still 
H  =  KV  (T  -  tc). 

The  heat  discharged  may  be  found  as  in  a  similar  case  with 
types  i  and  2. 

Total  heat  discharged  is 


The  efficiency  is 

Kp(T-  Q  - 


KV  (T  - 


T  - 


(»> 


Here  then  is  no  constant  relationship  between  T1  and  T  ; 
the  value  of  the  cycle  lies  between  cases  ist  and  2nd.  The 
efficiency  is  less  than  in  the  first  case,  but  greater  than  in  the 
second. 

Type  i  A.  —  In  this  type  of  engine  the  efficiency  cannot  be 
stated  in  terms  of  temperature  directly  because  of  the  nature  of  the 
perfect  cycle. 


54 


The  Gas  Engine 


U I    i     I     I     I    I     i    I     I     I     I     I     I     I     i     i     i     I 

fj      '2    -3     '4     '5      '6    '7     -8     -9  'I     '2     '3      4     -5     '6     -7      -o      -9 

1*0 

VOLUMES. 

*  absolute  temp.  CC.  at  £        >  absolute  pressure  at  £ 

*  ,,  „  /       A  „  „  f 

P° 
T  „.  „  e        i'v          volume  at          b 

T1  „  „  C  V  „  C 

f 

FIG.  17. — Type  3.     Perfect  diagram.     Incomplete  expansion. 


g 

7 



I 

n 

* 

£     f 

\ 

t"    5 



ft 

£ 

^^ 

•<      4 
g 

~~ 

•  * 

I  3 



% 

1; 

:,j|i^ 

c 

^^^i^^-T-pa^^-^-^-—  -|^_  | 

I 

12345            6789          10 

VOLUBIES 

FIG.  1 8  — Type  IA.     Perfect  diagram.      Limited  expansion. 


Thermodynamics  of  the  Gas  Engine  5  5 

The  expansion  line  is  adiabatic,  and  the  compression  line 
whereby  all  the  heat  is  discharged  is  isothermal.1 

Fig.  1  8  is  the  theoretical  diagram  of  such  an  engine.  The 
scale  is  altered  from  previous  diagrams  because  of  the  great  ex- 
pansion. 

There  is  no  compression  previous  to  the  addition  of  heat,  the 
heat  is  added  at  constant  volume  vot  which  is  the  volume  of  the 
charge.  The  pressure  rises  with  the  temperature  from  atmos- 
pheric pressure  /  and  temperature  /  to  maximum  pressure  PO  and 
temperature  T.  From  T  the  expansion  line  is  adiabatic,  and  is 
continued  far  enough  to  reduce  the  temperature  again  to  t.  The 
piston  then  returns,  compressing  the  gases  at  the  temperature  t  till 
the  original  volume  v0  and  pressure  /  are  attained. 

For  any  two  temperatures  /  and  T  there  is  evidently  a 
constant  relationship  between  the  available  work  and  work  dis- 
charged as  heat.  As  in  expanding  from  highest  to  lowest  tem- 
perature the  temperature  falls  from  T  to  /,  the  whole  area  cf 
the  diagram  T  v0  v  /,  may  be  taken  as  the  heat  supplied  to  the 
cycle. 

The  heat  rejected  is  discharged  at  constant  temperature  /,  and 
is  .equivalent  to  the  area  v0  v  1  1. 

For  any  adiabatic  curve  the  area  Tv0  v  t  is 

area  =  —  -1—  (p,  v0  -  p0  T).  (12) 

For  any  isothermal 

areaz/,27//  =  pv0  Log.  e  —  .  (13) 

The  efficiency  is  therefore  — 


1  In  Dr.  A.  Witz's  able  work,  Etudes  sur  les  moteurs  d  gaz  tonnant,  he  falls 
into  the  error  of  supposing  both  expanding  and  compression  lines  of  this  type  adi- 
abatic, and  he  accordingly  grea'ly  ovtr-estimates  the  efficiency  proper  to  it. 


56  The  Gas  Engine 

but,  as  the  line  of  compression  discharging  heat  is  an  isothermal, 
that  is,  the  temperature  is  kept  constant  at  t  during  compression 
from  the  lowest  pressure  to  atmosphere, 

pv0  =  p0v  (Boyle's  law). 
The  efficiency  may  therefore  be  written 

(y  -.)(>',  Log.  <^ 


E  =  I 


then  . 

t      P      \v          tuv.     \t 

The  efficiency  can  therefore  be  given  entirely  in  terms  of  T  and 
(y-  i)/Lqg.  cA 


E=T-  _  ±      —  •  (TS) 

T  -  / 

In  the  case  where  the  expansion  is  not  carried  far  enough  to 
bring  the  temperature  of  explosion  down  to  the  temperature  of  the 
atmosphere,  the  efficiency  can  be  found  by  using  the  formulae 
12  and  13  to  get  proportions  of  available  and  total  work,  and  then 
get  from  the  nature  of  the  compression  curve  the  total  heat  dis- 
charged. As  this  is  variable  it  will  be  better  to  study  it  from  a 
numerical  example  later  on. 

The  diagram  given  is  the  best  possible  for  this  kind  of  cycle. 

EFFICIENCY  FORMULAE  FOR  THE  DIFFERENT  TYPES. 

The  general  formulae  for  efficiency  of  the  four  kinds  of  cycle 
are  as  follows. 

TYPE  i,  ist  Case  : 


T1  in  terms  of  T  and  /: 


•-•6)*' 


Thermodynamics  of  the  Gas  Engine  57 

2nd  Case  : 

T  —  t  (17) 

TYPE  2,  ist  Case  : 

E  =  i  —    T   ~  *  ; 


also  E  =  i  —     — , 


(18) 

4' 


2nd  Case  : 

i  (Ti  _  /.)  +  (,i  _  f) 

~^~=7T  ('9) 

TYPE  3,  u/  Case  : 


'    T   -   tc  (20) 

T1  in  terms  of  T  and  /  : 


also  E  =  i  —  — 


(21) 


E  =   I    _  .- 

(22) 


TYPE  i  A  :    V 

/  (y  -  i)  Log.  e 

E=I""~  T-/  -'  (23) 

Those  formulae  will  be  found  very  convenient  in  rapidly  calcu- 
lating the  theoretical  efficiency  for  any  kind  of  diagram,  but  they 
do  not  throw  much  light  upon  the  relative  advantage  of  the  differ- 
ent types.  In  type  i,  for  instance,  it  is  apparent  that  efficiency 

increases  with  increase  of  temperature  because  the  fraction  T   ""  * 


5  8  The  Gas  Engine 

becomes  less  with  increase  of  T,  but  it  does  not  rapidly  become 
less  because  x1  also  increases  with  increase  of  T. 

In  type  2,  ist  case,  the  efficiency  is  quite  independent  of  T, 
and  is  dependent  only  on  the  ratio  between  /  and  tc  or  v0  and  vc. 
Increase  of  x  (maximum  temperature)  increases  the  available 
portion  of  the  engine  diagram,  and  therefore  the  average  pressure, 
but  without  altering  the  efficiency. 

TYPE  3. — With  this  type  it  is  easy  to  see  (ist  case)  that  the 
efficiency  is  greater  than  in  type  i,  but  only  a  numerical  example 
will  show  the  proportion. 

In  the  second  case  it  may  be  greater  or  less  than  in  type  i, 
depending  altogether  on  the  amount  of  the  compression. 

To  obtain  a  clear  idea  of  the  relative  values  of  the  efficiencies, 
it  is  necessary  to  calculate  a  few  numerical  examples. 

CALCULATED  EXAMPLES  OF  EFFICIENCY  OF  THE  TYPES. 
Numerical  Examples. — Using   air  as  the   working  fluid,    the 
value  of  y,  the  ratio  of  specific  heat  at  constant  volume  to  specific 
heat  at  constant  pressure  is  1-408. 

—t  =  y  —  i  -408. 

The  gaseous  mixture  used  in  a  gas  engine  differs  considerably 
from  pure  air  in  its  composition,  and  consequently  in  the  ratio 
between  specific  heat  at  constant  volume,  and  specific  heat  at  con- 
stant pressure,  but  it  is  advisable  in  the  first  place  to  consider  the 
cycle  as  using  air  pure  and  simple.  So  many  circumstances 
modify  the  theoretic  efficiency  in  actual  practice  that  they  can  be 
best  considered  after  studying  the  simpler  cases. 

The  temperature  1600°  C.  is  a  very  usual  one  in  the  cylinder 
of  a  gas  engine,  and  it  will  be  calculated  in  each  instance  as  the 
maximum,  17°  C.  being  taken  as  atmospheric  temperature. 

A  similar  set  with  1000°  C.  as  the  maximum  will  be  calcu- 
lated to  show  in  each  case  the  change  of  efficiency,  if  any,  with 
change  of  maximum  temperature. 

TYPE  i. — ist  Case.  The  expansion  is  continued  to  atmos- 
pheric pressure. 

Taking    x  —  1600°  C.  =  1873°  absolute. 
/  =      17°  C.  =    290°      „ 


Thermodynamics  of  the  Gas  Engine  59 

Then      x1  =  the  temperature   after  adiabatic   expansion   to 
atmospheric  pressure. 


TJ  = 

T1  =  290  fLJESjl^j  _  I09o°  absolute. 

The  efficiency  is 

T1  —  /  0  IOQO  —  200 

E  =  i  —  y  -      -  =  i  —  1-408  -  -  =  0*29 

T  -  /  1873  -  290 

E  =  0*29  with  maximum  temperature  of  1600°  C. 
Taking  the  maximum  temperature  of  explosion  as  1000°.  C. 

Absolute 
T  =     1273°  =  1000°  C. 

/=     290°=      i7°C. 
then    T1  =     829°. 

E  =  i  —  1*408    29 ? —  =  0*23.  . 

1273  -  290 

-E  =  0*23  with  maximum  temperature  of  explosion  as  1000°  C. 

In  this  cycle  the  efficiency  evidently  increases  with  increase  of 
the  temperature  of  the  explosion,  but  not  in  proportion  to  the 
increase  of  temperature  ;  a  change  of  maximum  temperature  from 
1000°  to  1600°  C.  only  causing  the  efficiency  to  rise  from  0-23 
to  0-29.  That  is,  at  the  first  temperature,  23  heat  units  out  of 
every  100  given  to  the  cycle  will  be  converted  into  work, 
while  with  the  second  much  higher  temperature,  only  29  units  of 
100  will  be  converted  into  work. 

The  second  case  of  this  type  is  the  one  most  commonly  occur- 
ring in  practice.  The  cylinder  is  so  arranged  that  the  charge  is 
taken  in  for  half- stroke,  the  explosion  then  occurs,  and  the  piston 
completes  its  stroke,  expanding  the  heated  gases  from  one  volume 
to  two  volumes. 

In  the  diagram,  fig.  12,  suppose  volume   v  to  be  equal   to 

2  vn  and 

T  =  1873°  absolute. 
/  =     290° 
To  get  T1, 


60  The  Gas  Engine 


/  T  \  o'4oS 

=  1873  (  —  )       =  1411 


absolute. 


To  calculate  efficiency  /]  is  still  required  ;  it  is,  in  terms  of 
volume  and  /, 

/!  =  _  /  =  -290  =  580°  absolute. 
The  efficiency  can  now  be  obtained  from  formula  (17). 


_  r  (1411  —  580)  +  1-408(580  —  290) 
1873  -  290 

=  i  -  83^1:408^90  =  0.22  nearl 

1583 

For  this  case  E  =  0*22, 

showing  the  effect  of  limiting  the  expansion  and  discharging  at  a 
pressure  above  atmosphere. 

Taking  the  same  ratio  of  expansion  and  the  lower  maximum 
temperature  of  1000°  C. 

T  =  1273°  absolute. 
/  =    290° 

(ijf\  y  -  i  /  T  \  °'4°^ 

_j       =  1273  f  -J       =  959°  absolute, 

and  /]  is  still  290  x  2  —  580°  absolute. 
Therefore  E  =  o-2o. 

Here  the  diminution  of  efficiency  due  to  diminished  expan- 
sion is  not  so  great  as  in  the  first,  or  rather  the  higher,  tempera- 
ture, 

with  complete  expansion     1000°  C.  giving  0^23, 
„    limited  „  1000°  C.        „     0*20  ; 

with  the  higher  temperature  of  1600°  C., 

with  complete  expansion     1600°  C.  giving  0*29, 
„     limited  „  1600°  C.      „      0-22. 

It  is  evident  from  these  results  that  where  the  amount  of  ex- 


Thermodynamics  of  the  Gas  Engine  6  1 

pansion  is  from  one  volume  to  two  volumes,  as  in  the  Lenoir  and 
Hugon  engines,  the  efficiency  does  not  substantially  improve  with 
increasing  temperature. 

TYPE  2.  —  \st  Case.  Where  the  expansion  is  carried  far  enough 
to  reduce  the  working  pressure  to  atmosphere,  the  efficiency  of 
this  kind  of  engine  is  quite  independent  of  the  temperature  of 
combustion.  This  is  shown  by  Professor  Rankine  l  in  his  work  on 
the  steam  engine.  Whether  the  heat  added  after  compression 
be  great  or  small  in  amount,  the  proportion  of  it  which  is  con- 
verted into  work  is  stationary. 

The  compression  most  commonly  used  in  this  kind  of  engine 
is  60  Ibs.  per  sq.  in.  above  atmosphere,  75  Ibs.  per  sq.  in.  absolute, 
taking  the  atmospheric  pressure  as  15  Ibs.  per  sq.  in. 

The  compression  is,  as  before  stated,  adiabatic  ;  no  heat  is 
lost  or  gained.  The  temperature  rises  simply  because  of  work 
performed  upon  the  air. 

Let 

Atmospheric  temperature  and  pressure  (absolute)  t,p  =  290°  —  15 
Compression,  „  „  „  4A=  ~75 


H?)'- 
'•='(!)''" 


tc  =  290  =  462-5°  absolute, 

2QO 

E  =   I    -    -/—  =  0'37 
462-5 

£  =  0-37. 

This  result  is  much  better  than  any  obtained  with  the  first 
type.  It  holds  equally  good  for  all  combustion  temperatures  ; 
with  either  1000°  C.  or  1600°  C.  the  efficiency  would  still  be 
0-37,  so  long  as  that  degree  of  compression  was  used.  With  a 
higher  compression  the  efficiency  increases  ;  100  Ibs.  per  sq.  in. 
above  atmosphere  is  quite  a  workable  degree  of  compression.  It 
is  instructive  to  calculate  the  efficiency  with  this  pressure  : 

1   The  Steam  Engine,  Prof.  Rankine,  p.  373,  Formula  (7). 


62  The  Gas  Engine 

t    —  290°  absolute. 

p  —    15  Ibs.  per  sq.  in.  absolute. 

(I    I    C  \    0.29 
°  )      =  524°  nearly. 


524 

E  =  0-45- 

This  type  is  evidently  much  superior  to  the  first  type,  as  it  i? 
capable  of  greatly  increased  efficiency  by  the  mere  increase  of 
compression. 

In  the  engines  in  practice  expansion  has  not  been  carried  far 
enough  to  give  the  results  calculated  above.     It  has  been  usual  to 
construct  the  engine  so  that  the  compression  pump  is  one-half  of 
the  volume  of  the  motor  cylinder,  that  is,  the  ratio  of  the  expan- 
sion is  from  one  volume  to  two  volumes  at  atmosphere.     Taking 
first  a  compression  of  60  Ibs.  per  sq.  in.  above  atmosphere  with  this 
proportion  between  the  volumes  at  atmosphere,  and  the  highest 
temperature  as  1600°  C,  then  (diagram,  fig.  13) 
T  =  1873°  absolute. 
t  —  290°        „ 
4  =  462-5°     » 

t1  =  290    X    2  =  580. 

Before  getting  T1  it  is  necessary  to  get  the  volume  z>  at  the 
highest  temperature.  It  is 


and 


and         T'  =  T  *  =  1873(12?)°'*  =  I566°  absolute. 

The  efficiency  can  now  be  found  by  formula  (19) 


E  2s:  i  — 


1873  —  462-5 


Thermodynamics  of  the  Gas  Engine 


_  ==Q 


1410-5 

E  ==-  0'30. 

Here  the  insufficient  expansion  has  caused  the  efficiency  possible 
from  the  compression  to  fall  from  0-37  to  0^30. 

Calculating  in  the  same  way  for  the  greater  compression  of 
100  Ibs.  per  sq.  in.  above  atmosphere,  with  expansion  ratio  between 
compression  and  motor  cylinders  of  two,  it  is  found  that  the  result 
is  improved. 

Here  vc  =  0-235  vol. 

and  vp  =  0-841  vol. 


T    =  T 


/  =  290° 

Jfl==  580° 

'c=  5240 

The  efficiency  is  therefore 


0-71  (1318  — 


1873-524 

=  i  _  °171_x_  738_+_29o    =  !  _    8l4  =  0-40 
1349  1349 

E  =  0-40. 

The  greater  compression  has  greatly  increased  the  efficiency 
while  leaving  the  proportion  of  the  two  cylinders  unaltered. 

Still  using  the  same  cylinders,  the  efficiency  with  compression 
of  60  Ibs.  above  atmosphere  and  a  maximum  temperature  of 
1000°  C,  is 

E  =  0*28  nearly, 

the  data  being 


T1  =     892° 
/'  =     580° 


volumes 


T  -1273° 
/  =  290° 
tc  =  462°, 

V     =         2 


?>=  °'3l8 


0'4  The  Gas  Engine 

Using  the  higher  compression  100  Ibs.  above   atmosphere  with 
1000°  C.  as  highest  temperature 

£  =  0-44. 

Data:  T>=     763°  T  =  1273° 

/i  =     580°  /   =    290° 

t<  =     524° 
Vol.  :  v0  —         i  v  —        2 

vc~         0-235  vp=        0-57 

In  this  kind  of  engine  the  best  result  is  always  obtained  when 
the  expansion  is  carried  to  atmospheric  pressure.  The  necessary 
proportion  between  the  two  cylinders,  to  accomplish  this,  depends 
on  two  things  :  the  temperature  of  compression,  and  the  tempera- 
ture of  combustion.  The  ratio  between  the  cylinders  should  be 

,=  i. 

With  a  temperature  of  compression  of  462°,  for  instance, 
and  a  maximum  of  1873°  absolute  (*  7-3  =  4'°5)  the  volume  of 

the  motor  cylinder  would  require  to  be  4-05  times  that  of  the 
pump.      With   the  increased   compression  giving  524°  absolute 

( J— ^-=  3*57  j  ratio  of  motor  to  pump  3^57  to  i. 
\  524  / 

With  the  lower  maximum  temperature  of  1273°  the  ratios  for 
the  two  compression  values  are 

I273  _  2.yj-  _  73  __  2-.*  nearly. 

462  524 

These  figures  explain  why  the  efficiency  varies  so  much  with 
two  cylinders  of  ratio  i  to  2  with  change  of  maximum  temperature 
and  compression. 

TYPE  3. —  ist  Case.  In  this  case  expansion  is  carried  to  atmo- 
sphere.    It  is  evident  from  the  formulae  that  efficiency  varies  to     j 
some  extent  with  maximum  temperature  of  the  explosion. 

Taking  first  a  maximum  temperature  of  1600°  C.,  as  in  the  last 
type  calculated,  with  a  pressure  of  compression  60  Ibs.  above 
atmosphere, 

The  data  are  as  follows  : 

Temperatures  T=i873°         ^  =  290 

*r.   =   462. 


Thermodynamics  of  the  Gas  Engine  55 


Tl  in  terms  of  T  and  /,  tc  is  (see  p.  57) 


T1   =   783°. 

The  efficiency  therefore 

E  =  i  -  y  Tl~^   =  i  -  1-408  __783_^2_?? 

T     -    tc  1873  —  462 

E   =   0'5I. 

With  compression  100  Ibs.  above  atmosphere, 
and  T1  is  therefore  T1  =  290   |LJL3\r4^8  =  545° 

l873  ~  524 
E  =  073. 

Taking,  next,  1000°  C.  as  the  highest  temperature,  first  with 
the  lower  compression,  and  after  with  the  higher  compression, 
with  60  Ibs.  compression  T1  is  595°  absolute 
with  100  „  T1  is  545°         „ 

E  =  0-47  at  60  Ibs.,  E  =  0-52  at  100  Ibs.,  with  1000°  C. 

In  this  case  the  efficiency  varies  both  with  the  maximum  tem- 
perature of  the  explosion  and  the  compression  temperature  previous 
to  explosion.  A  glance  at  the  numbers  placed  together  will  show 
clearly  the  relationship. 

Max.  temps,  in  °C.          ...  1600°  1600°  1000°  1000° 
Pressure  of  compression  above  atmo- 
sphere            60  Ibs.  100  Ibs.  60  Ibs.  100  Ibs. 

Efficiency        .         .         .         .         .  o'5i            073  0-47  0-52 

2nd  Case. — Here  the  expansion  after  explosion  is  not  carried 
on  far  enough  to  reduce  the  pressure  to  atmosphere.  It  terminates 
when  the  volume  is  the  same  as  existed  before  compression,  that  is, 
the  volume  swept  by  the  motor  piston  in  expanding  doing  work  is 
identical  with  that  swept  by  the  pump  piston  in  compressing  up  to 
maximum  pressure.  Pump  and  motor  are  equal  in  volume.  To  this 
case  of  type  3  belong  all  compression  engines  in  which  the  motor 
piston  compresses  its  charge  into  a  space  at  the  end  of  the  cylinder. 

F 


66  The  Gas  Engine 

In  this  case,  as  in  case  i,  type  2,  the  theoretic  efficiency  of  the 
engine  is  quite  independent  of  the  maximum  temperature  of  the 
explosion.  So  long  as  the  volume  after  expansion  is  the  same  as 
that  before  compression,  it  does  not  matter  in  the  least  how  much 
heat  is  added  at  constant  volume  of  compression  ;  whether  only  a 
few  degrees  rise  occurs  or  1000°  or  2000°,  it  is  all  the  same  so 
far  as  the  proportion  of  added  heat  converted  into  work  is  con- 
cerned. That  proportion  depends  solely  upon  the  amount  of 
compression. 

For  60  Ibs.  adiabatic  compression,  temperature  462°  absolute, 
the  efficiency  is  0*3  7  ;  for  i  oo  Ibs.  above  atmosphere  it  is  0*45.  Given 

by  the  formula  E  =  i  -      -  .    (See  p.  57.) 

*<r 

E  depends  absolutely  upon  the  temperature  of  the  atmosphere 
and  the  temperature  of  compression  /  and  tc.  If  the  relative 
volumes  of  space  swept  by  piston  and  compression  space  be  known, 
then  the  efficiency  can  be  at  once  calculated. 

$rd  Case.  —  Here  the  expansion  is  carried  further  than  the 
original  volume  before  compression,  but  not  far  enough  to  reduce 
the  pressure  to  atmosphere.  Efficiency  is  always  less  than  in  the 
first  case  with  corresponding  temperature  of  explosion  and  compres- 
sion, but  greater  than  in  the  second  case.  It  is  found  by  the 
formula  : 

1    -/'j+.yft1    ~t) 


T    -   te 

tx  depends  on  the  relationship  between  the  volumes  v0  and  v  the 
volume  at  atmosphere  and  the  volume  of  discharge  after  expansion. 
it  is  always  : 


T1  is  also  found  by  the  same  method  as  in  types  i  and  2.    It  is 
better  to  postpone  calculating  any  particular  case  of  tbis  at  present,  ; 
as  no  engine  doing  this  has  yet  got  into  public  use,  and  it  can  be  ' 
considered  further  on  in  discussing  the  effect  of  increased  expan-  • 
sion  in  the  actual  engines. 

Type  i  A.  —  The  efficiency  of  this  type  of  heat  cycle  depends  : 
to  a  considerable  extent  upon  cooling  during  the  return  stroke  ; 
in  its  best  form,  cooling  at  the  lowest  temperature  during  isother- 


Thermodynamics  of  the  Gas  Engine  67 

mal  compression,  it  cannot  be  carried  out  without  introducing  the 
very  disadvantages  with  which  the  hot-air  engine  was  saddled, 
namely,  a  dependence  upon  the  slow  convection  of  air  for  the 
discharge  of  the  heat  necessarily  rejected  from  the  cycle.  The 
rapid  performance  of  this  operation  is  impossible,  and  accordingly 
it  is  hardly  fair  to  compare  this  type  with  those  preceding  ;  they. 
could  all  of  them  be  greatly  improved  in  theory  by  introducing 
greater  expansions  and  cooling  by  convection  at  the  lowest  tempe- 
rature, but  all  at  the  expense  of  rate  of  working.  The  efficiency 
of  type  i  A,  will  be  found  to  be  high  ;  but  it  is  to  be  kept  con- 
stantly in  mind  that  the  penalty  of  slow  rate  of  work  was  fully 
exacted  in  the  practical  examples  of  the  kind  in  public  use.  They 
are  exceedingly  cumbrous,  and  give  but  a  trifling  power  in  com- 
parison with  their  bulk  and  weight.  The  efficiency  in  this  type  is 
dependent  upon  T  and  /  only. 


E  =  !  _ 


T  —  t 

Take  first  T  =  1873° 

/=    290° 
0-408^  x  4-57 

~ 


E  =  0-66. 

This  is  a  very  high  efficiency,  but  it  is  obtained  by  using  an 
enormous  expansion, 

~  =  (y)^1  =  96'7  nearly. 

The  piston  must  move  through  nearly  100  times  the  original 
volume  of  the  charge  before  the  temperature  is  reduced  to  the 
temperature  existing  before  igniting  ;  in  passing  back  to  unit 
volume  the  gases  must  be  supposed  to  keep  at  t  by  the  cooling 
effect  of  the  cylinder  walls. 

\Vhen  T  =  1000°  C.  =  1273°  absolute, 

/=      17°  C.  =    290°       „ 
the  efficiency  is 

E  =  0-56, 
and  the  expansion  required  is  not  £o  great,  being  37-5  volumes. 

F  2 


68 


The  Gas  Engine 


The  actual  ratios  of  expansion  used  in  practice  have  not  ap- 
proached those  proportions,  and  will  be  considered  while  discuss- 
ing the  diagrams  taken  from  engines  of  this  type. 

COMPARISON  OF  RESULTS. 

The  two  maximum  temperatures  used,  1600°  C.  and  1000°  C., 
with  the  lowest  temperature,  17°  C.,  give  in  a  perfect  heat-engine, 
efficiencies 

1600°  C.  =  0-85  nearly, 

1000°  C.  =  077      „ 

One  case  in  type  3  comes  nearer  to  a  perfect  heat-engine  than 
any  of  the  others.  To  compare  easily  the  following  table  will  be 
useful. 

TABLE  OF  THEORETIC  EFFICIENCY. 


Max.  temp.  °C. 

Compression 

Efficiency 

Temp. 

Pressure 

Type  i. 

abs.°C. 

above  atmos. 

Expanding  to  atmosphere 

1600° 

0'29 

i  >             »             ii 

1000° 

— 

— 

0-23 

Expanding  to  twice  volume 

)           1600° 

— 

— 

0'22 

existing  before  ignition 

f              1000° 

— 

— 

O'2O 

Type  2. 

Expanding  to  atmosphere 

— 

462° 

60  Ibs. 

°'37 

»             »             >i 

— 

524° 

100  Ibs. 

0-45 

(1600° 

462' 

60  Ibs. 

0-30 

Expanding  to  twice  volume 

IGOO° 

524° 

100  Ibs. 

0-40 

existing  before  compression 

ICOO3 

462° 

60  Ibs. 

0-28 

1000° 

524° 

100  Ibs. 

0-44 

Type  3. 

Expanding  to  atmosphere 

1600° 

462° 

60  Ibs. 

0-51 

..                             M                              .1 

1600° 

524° 

100  Ibs. 

073 

ti            11            11 

1000° 

462° 

60  Ibs. 

0-47 

•I            11            ii 

IOOO3 

5240 

100  Ibs. 

0-52 

Expanding    to     the     same 

) 

volume  as  existed  before 

f 

462° 

60  Ibs. 

0'37 

compressing 

)               i 

^24° 

100  Ibs. 

o'4<; 

Expanding  to  greater  volume 
than  existed  before  com- 

! Efficiency  between  ist  and  2nd  cases  of  this  type 

pressing,  but  not  enough 
to  reach  atmosphere 

1      depending  on  ratio  of  expansion. 

Type  i  A. 

Expa-nding  from  max.  temp. 

1600°                         — 

0-66 

to  lowest  temperature 

icoo3                          — 

0-56 

Tliermodynamics  of  the  Gas  Engine  69 

Comparing  first  the  best  results  of  each  type,  it  is  evident  that 
type  i  is  the  least  perfect  as  a  heat-engine,  giving  back  only  0*29 
of  the  total  heat  entrusted  to  it  as  mechanical  work,  and  rejecting 
the  rest  of  the  heat.  Type  2  is  distinctly  better,  giving  a  maximum 
efficiency  of  0*45,  or  nearly  half  the  heat  converted  into  work. 

Type  i  A,  with  a  heat  conversion  of  o'66,  is  still  better  ;  but 
type  3,  with  073  efficiency,  is  best  of  all,  coming  very  closely 
indeed  to  what  a  perfect  cycle  is  capable  of  giving. 

It  cannot  be  too  constantly  kept  in  mind  that  it  by  no  means 
follows  that  the  best  theoretic  efficiency  will  give  the  best  result  in 
practice.  If  gained  at  the  expense  of  great  volume  or  an  imprac- 
ticable process,  it  may  not  be  worth  so  much  as  a  worse  cycle 
where  small  volume  of  cylinder  and  an  easy  process  make  it  more 
easily  attainable.  Type  i  A  is  at  -a  great  disadvantage  in  the 
matter  of  expansion  ;  it  requires,  as  has  been  shown,  expansion  of 
967  and  37*5  volumes  respectively,  so  great  that  it  is  practically 
out  of  comparison  as  a  workable  cycle  with  the  others.  The 
other  cycles  vary  in  this  respect  also,  but  the  variation  will  fall 
under  the  consideration  of  mechanical  efficiency  at  a  later  stage. 
Type  i  A  is  so  much  out  that  it  was  necessary  to  mention  it  here. 

In  type  i,  the  efficiency  varies  with  the  temperature  of  explo- 
sion, especially  where  the  expansion  is  carried  to  atmosphere  ;  the 
difference,  however,  is  not  great,  a  very  large  increase  of  maximum 
temperature  but  slightly  increasing  the  efficiency,  IQOO°  C  giving 
0-23,  and  1600°  C.  only  0*29,  of  heat  conversion.  When  the 
expansion  is  limited  to  twice  the  volume  at  the  moment  of  heat- 
ing, the  effect  of  increasing  temperature  in  increasing  the  efficiency 
is  almost  nil,  1000°  C.  giving  0*20  efficiency,  and  1600°  C.  only 
o'22  efficiency.  The  conclusion  to  be  drawn  from  the  fact  is  this  : 
in  engines  of  the  Lenoir  or  Hugon  kind,  with  limited  expansion, 
the  economy  is  not  increased  by  using  high  temperatures  ;  a  weak 
mixture  will  give  as  good  an  indicated  efficiency  as  a  strong  one. 

With  type  2,  the  maximum  efficiency  is  obtained  by  expand- 
ing to  atmospheric  pressure,  and  in  this  case  it  is  quite  independent 
of  the  temperature  of  combustion;  it  does  not  matter  whether  a  great 
or  small  increase  of  temperature  occurs  at  the  pressure  of  compres- 
sion, the  efficiency  remains  the  same.  That  is,  whether  much  heat 
be  added  or  little  heat,  the  proportion  converted  into  work  depends 


yo  TJie  Gas  Engine 

on  one  thing  only,  that  is,  the  amount  of  compression  —  the 
greater  the  compression  the  greater  the  efficiency  of  the  engine. 
The  pressures  of  compression  which  have  been  calculated,  are 
pressures  which  have  been  used  for  the  kind  of  cycle  in  practice. 
The  only  limits  to  increasing  compression  are  the  practical  ones  of 
strength  of  engine  and  leakage  of  piston.  The  difference  between 
efficiency  at  60  Ibs.  and  100  Ibs.  compression  above  atmosphere  is 
considerable,  the  first  giving  E  =  0-37,  the  second  E  =  0-45. 

When  the  expansion  is  limited  to  twice  the  volume  existing 
before  compression  the  maximum  temperature  then  affects  the  effi- 
ciency, but  not  to  such  an  extent  as  the  compression. 

Type  3. — This  is  the  best  type  of  all  from  the  point  under  con- 
sideration. The  efficiency  in  the  best  form  of  it  varies  both  with 
maximum  temperature  and  pressure  of  compression.  At  1600°  C. 
maximum  temperature  and  compression  60  Ibs.  per  square  inch 
above  atmosphere,  E  =  0*51.  At  the  same  maximum  tempera- 
ture but  the  higher  compression  of  100  Ibs.  above  atmosphere, 
it  rises  to  the  high  efficiency  of  073,  which  is  very  nearly  what  a 
perfect  heat-engine  using  1600°  C.  and  atmospheric  temperature 
could  give.  With  maximum  temperature  of  1000°  C.  for  these 
two  compression  pressures  the  efficiencies  are  E  =  0-47  and  E  = 
0*52.  The  best  case  of  this  type  is  not  the  one  occurring  in 
practice,  in  fact  no  compression  engine  of  this  kind  has  ever  been 
much  which  expands  to  atmosphere  Usually  expansion  is  only 
carried  to  the  same  volume  as  existed  before  compression,  and 
there  the  efficiency  is  quite  independent  of  the  maximum  tempera- 
ture; it  is  determined  by  compression  solely  as  in  type  2. 

For  compression  60  Ibs.  per  square  inch  above  atmosphere  it 
is  0-37,  and  for  100  Ibs.  per  square  inch  above  atmosphere  it  is 
0-45,  the  difference  between  types  2  and  3  in  this  case  being, 
that  type  2  expands  its  working  fluid  at  the  pressure  of  compres- 
sion, which  remains  constant,  and  the  pressure  falls  to  the  pressure 
of  atmosphere  by  the  movement  of  the  piston  doing  work;  in 
type  3  the  heat  is  added  to  the  working  fluid  at  constant  volume, 
pressure  increasing,  then  expansion  doing  work,  till  volume 
before  compression  is  attained.  The  one  acts  by  increase  of  the 
volume  of  the  working  fluid  by  heat,  the  other  by  increase  of 
pressure  of  the  working  fluid  by  heat.  The  one  engine  gives 


Thermodynamics  of  the  Gas  Engine  7 1 

large   volumes,    low    pressures;   the  other    small   volumes,   high 
pressures. 

In  type  i  A,  the  change  of  volume  required  is  so  great  that  its 
efficiency  cannot  be  fairly  compared  with  the  others. 

Conclusions. — The  best  cycle  for  great  efficiency  is  produced 
by  using  compression  in  the  manner  of  type  3. 

In  any  cycle  with  any  definite  expansion,  increase  of  compression 
previous  to  heating  produces  increase  of  the  proportion  of  heat 
converted  into  work.  In  some  cases  of  compression  cycles,  increase 
of  the  highest  temperature  does  not  increase  the  efficiency; 
it  may  even  diminish  it. 

There  are  cases  in  types  2  and  3  when  the  efficiency  is  quite 
independent  of  the  maximum  temperature,  depending  solely  on 
the  amount  of  compression  employed. 


The  Cas  Engine 


CHAPTER   IV. 

THE    CAUSES    OF    LOSS    IN    GAS    ENGINES. 

IN  calculating  the  efficiency  of  the  different  kinds  of  engines,  it 
has  been  assumed  that  the  conditions  peculiar  to  each  cycle 
have  been  perfectly  complied  with.  In  actual  engines  this  is 
impossible  ;  it  is  therefore  necessary  to  discover  in  what  manner 
practice  fails  in  performing  the  operations  required  by  theory. 

The  actual  engines  differ  from  the  ideal  ones  in  several 
ways  : 

1.  The  working  fluid  loses  heat  to  the  walls  enclosing  it  after 
its  temperature  has  been  raised  to  the  highest  point ; 

2.  The    working    fluid    often    gains   heat    when    entering  the 
cylinder  at  a  time  when  it  should  remain  at  the  lowest  tempera- 
ture; 

3.  The  supply  of  heat  is  never  added  instantaneously  as  is  re- 
quired in  some  types  ; 

4.  The  working  fluid  does  not  behave  as  a  perfect  gas  ;  owing 
to  the   complex  phenomena  of  combustion,  to  some  extent  its 
physical  state  is  changed  during  the  addition  of  heat ; 

^.  The  admission,  transfer  and  expulsion  of  the  working  fluid 
are  not  accomplished  without  some  resistance,  wire-drawing  during 
admission,  back-pressure  during  exhaust. 

The  first  cause  of  loss  is  by  far  the  most  considerable  and  will 
be  considered  first. 

Loss  OF  HEAT  TO  THE  CYLINDER  AND  PISTON. 

Although  this  is  the  most  considerable  source  of  loss  in  all 
gas  engines,  the  stock  of  information  in  existence  upon  the  subject 
is  quite  insufficient  to  justify  any  attempt  to  state  a  general  law. 
So  far  as  the  author  is  aware,  no  experiments  have  yet  been  made 


The  Causes  of  Loss  in  Gas  Engines  73 

to  determine  the  rate  at  wh:cha  mass  of  heated  air,  at  from  1000° 
to  1600°  C.  loses  heat  to  the  comparatively  cool  metal  surfaces 
which  enclose  it.  That  the  rate  of  flow  is  rapid  is  quite  evident. 
Otherwise,  it  would  be  impossible  to  raise  steam  with  the  relatively 
small  heating  surfaces  generally  used  in  boilers.  Before  applying 
the  efficiency  values  obtained  to  actual  practice  it  is  necessary  to 
know  at  what  rate  a  cubic  foot  of  air  at  about  1600°  C.  in  contact 
with  metal  walls  at  from  17°  C.  to  100°  C.  will  lose  heat:  also  to 
know  how  that  rate  changes  with  change  of  temperature  and 
density.  Much  is  known  of  the  laws  of  cooling  at  lower  tem- 
peratures, but  little  positive  data  exist  for  temperatures  so  high 
as  those  occurring  in  the  gas  engine.  A  hot  gas  loses  heat  to  the 
colder  walls  enclosing  it  mainly  by  circulation  or  convection.  The 
conductivity  of  gases  for  heat  is  very  slight,  and  unless  in  some 
way  a  large  surface  of  the  gas  is  exposed  to  the  cooling  surface, 
practically  no  heat  would  escape  from  the  working  fluid  in  the  short 
time  during  which  it  is  exposed  in  gas  engines.  Any  arrangement 
which  favours  or  hastens  convection  will  therefore  increase  loss  by 
increasing  the  extent  of  hot  gaseous  surface  exposed  to  the  walls. 
The  smaller  the  surface  to  which  a  given  volume  of  working  fluid 
is  exposed  the  less  heat  will  it  lose  in  a  given  time.  So  far  as 
loss  of  heat  is  concerned  then,  the  best  type  of  engine  is  that 
which  exposes  a  given  volume  of  working  fluid  to  the  smallest 
surface  in  performing  its  cycle.  Suppose  that  in  the  three  types 
the  pistons  move  at  the  same  velocity,  then  that  which  requires  to 
move  through  the  smallest  volume,  the  areas  of  the  pistons  being 
supposed  equal,  will  take  the  shortest  time  to  perform  its  cycle.  In 
the  first  engine  the  piston  moves  through  27  vols.,  with  the  hot  air 
filling  the  cylinder;  the  second,  through  37  vols.;  and  the  third, 
through  2-4  vols.  (see  diagrams  u,  13  and  15).  As  the  volumes 
are  proportional  to  the  time  taken  to  perform  each  cycle  the 
third  type  has  the  best  of  it,  the  time  of  exposure  of  the  hot 
working  fluid  being  the  least  ;  the  second  type  is  worse  than 
the  first.  There  is  still  another  circumstance  in  addition  to 
surface  exposed  and  time  of  exposure,  that  is,  the  average 
temperature  of  the  hot  gas  which  is  exposed.  If  the  average 
temperature  is  lower  in  one  type  than  in  another  during  ex- 
posure to  a  given  surface  for  a  certain  time,  then  obviously 


74  The  Gas  Engine 

Jess  heat  will  be  lost  in  the  one  than  in  the  other.  Comparing 
the  average  temperatures  it  is  found,  that  in  the  first  the  tempera- 
ture ranges  from  1600°  C.  to  817°  C. ;  in  the  second  from  1600°  C. 
to  901°  C.  ;  and  in  the  third  from  1600°  C.  to  510°  C.  The 
third  will  therefore  show  a  lower  average  temperature  than  the 
others.  Three  conditions  are  requisite  in  the  engine  which  is  to 
lose  the  minimum  of  heat  from  its  working  fluid  : 

1.  In  performing  its  cycle  it  should  expose   a   given   volume  of 

its  working  fluid  to  the  least  possible  cooling  surface ; 

2.  It  should  expose  it  for  the  shortest  possible  time ; 

3.  The  average  temperature  during  the  time  of  exposure  should 

be  as  low  as  possible — 

which  conditions  are  best  fulfilled  by  the  third  type.  In  ad- 
dition to  its  advantage  in  theoretic  efficiency  it  possesses  the 
further  good  points  in  practice  of  proportionally  small  cooling 
surfaces,  short  time  of  exposure,  and  rapid  depression  of  tempera- 
ture due  to  work  done,  consequently  small  loss  of  heat  to  the 
cylinder  and  piston. 

The  diagrams,  figs,  n,  13  and  15,  have  been  selected  from  the 
others  belonging  to  each  type  because  the  pressures,  temperatures, 
and  relative  volumes  closely  correspond  with  those  which  would 
be  best  and  at  the  same  time  readily  practicable. 

The  flow  of  heat  really  occurring  in  the  gas  engine  cylinder 
will  be  discussed  when  the  actual  diagrams  come  under  considera- 
tion ;  meantime,  it  is  sufficient  to  have  proved  that  the  third  type 
will  in  practice  give  results  more  closely  approaching  its  theory 
than  the  others.  If  in  each  case  a  constant  proportion  of  the 
heat  supplied  were  lost  to  the  cylinder  and  piston,  the  ratio  of  the 
efficiencies  would  remain  constant,  and  although  it  would  be  im- 
possible from  present  data  to  predict  the  actual  values,  yet 
the  relative  values  would  be  known. 

GAIN  OF  HEAT  BY  THE  WORKING  FLUID  WHEN  ENTERING 

THE    EjSTGINE. 

In  all  types  of  gas  engine  it  is  found  most  economical  to  keep 
the  motor  cylinders  as  hot  as  possible ;  they  are  generally  worked 
at  a  temperature  close  upon  the  temperature  of  boiling  water. 
This  is  done  to  diminish  the  loss  of  heat  from  the  explosion.  It 


The  Causes  of  Loss  in  Gas  Engines  7  5 

follows  that  if  the  working  fluid  is  introduced  at  a  lower  temperature 
it  becomes  heated.  In  the  first  type,  the  charge  should  be  admitted 
and  remain  at  the  lowest  temperature  until  the  moment  of  explosion, 
which  is  of  course  impossible  if  the  cylinder  is  at  100°  C.  As  the 
piston  itself  is  hotter  than  that,  it  may  be  supposed  that  the  charge 
is  heated  to  that  point. 

Taking  an  extreme  case  and  calculating  the  effect  of  having 
an  absolute  temperature  of  390°  for  the  lower  limit,  it  will  be 
found  that  the  efficiency  is  diminished.  In  case  i,  type  i,  where 
the  expansion  is  carried  to  atmosphere  with  a  maximum  tem- 
perature of  1873°  absolute  =  1600°  C.,  the  value  becomes  reduced 
to  0-23. 

With  a  maximum  temperature  of  1 2  7 3°  absolute  =  1 000°  C  the 
efficiency  is  o'i6. 

TYPE  I. 


Initial  temp,  of  working 
fluid 

Max.  temp. 

Efficiency 

17°  C. 
117?  C 

i7JC 
n7°C. 

1600°  C. 
1600°  C. 
icoo°  C. 
iooo3C. 

0-23 
0-23 
o'i6 

Here  heating,  while  introducing  the  charge  will  always  cause 
diminution  in  efficiency,  the  proportion  of  loss  being  greater  with 
the  lower  maximum  temperature.  At  1600°  C.  the  loss  is  nearly 
one-fifth,  while  at  1000°  C.  it  is  close  upon  one- fourth. 

It  is  very  difficult  to  say  whether  it  is  better  to  work  with  the 
cylinder  hot  or  cold.  The  constructor  finds  himself  in  a  dilemma 
if  the  cylinder  is  kept  as  cold  as  the  surrounding  air  ;  then  the 
hot  gases  cool  more  rapidly.  If  he  keeps  the  cylinder  hot  to  diminish 
this,  the  efficiency  falls  also.  Experiment  alone  can  decide  the 
question. 

In  engines  of  type  2  it  is  a  usual  proceeding  to  leave  the 
compression  cylinder  entirely  without  water-jacketing,  under  the 
impression  that  heat  is  thereby  saved;  the  temperature  consequently 
rises  to  very  nearly  that  of  compression,  and  the  entering  charge 
becomes  considerably  heated  before  compression.  This  is  especi- 
ally the  case  if  the  admission  area  is  small,  and  throttling  occurs  ;  all 


76  The  Gas  Engine 

the  energy  of  velocity  of  the  entering  gas  becomes  transformed  into 
heat.  As  in  the  previous  case  the  charge  may  be  considered  to  rise 
to  117°  C.  before  compression. 

Where  expansion  is  carried  to  atmosphere  it  has  been  shown 
that  the  efficiency  is  quite  independent  of  the  maximum  tempera- 
ture, but  is  determined  by  one  circumstance  only  —  the  amount  of 
the  compression.  As 

F,  =  i  —  -  *  and  /  is  the  temperature  absolute  before  compressing 


/  /    ,  \    r  —  i 

and  as  -£  =  {—-}    *  ,  it  follows  that  with  a  constant  ratio  between 

t        \p  ) 

the  pressures  before  and  after  compression,  the  ratio  of  temperature 
before  and  after  compressing  will  also  remain  constant  ;  that  is, 
the  efficiency  is  not  in  any  way  affected  by  heating  the  working 
fluid,  provided  the  same  degree  of  compression  is  used.  Increase 
of  temperature  previous  to  compression  causes  a  proportional  in- 
crease of  temperature  after  compressing  without  in  any  way  disturb- 
ing the  ratio  between  them. 

This  is  an  important,  if  in  appearance  a  somewhat  paradoxical 
fact,  and  it  may  be  stated  in  another  way  : 

If  an  engine  receives  all  its  supply  of  heat  at  one  pressure, 
and  rejects  all  its  waste  heat  at  another  pressure,  after  falling 
from  the  higher  to  the  lower  pressure  by  expansion  doing  work, 
the  efficiency  is  constant  for  all  maximum  temperatures  of  the 
working  fluid. 

The  proportion  of  heat  converted  into  work  is  not  changed  in 
any  way  by  increasing  the  temperature  before  compressing,  and 
if  only  one  degree  of  heat  be  added  after  compressing,  the  same 
proportion  of  that  one  degree  is  converted  into  work,  as  would  be 
done  with  any  addition  of  heat  however  great. 

Where  the  expansion  is  not  continued  enough  to  reduce  the 
pressure  after  heating,  to  atmosphere,  as  in  the  cases  of  this  type 
which  occur  in  practice,  this  is  not  quite  true  ;  the  compression 
still  remains  the  most  powerful  element  of  efficiency,  but  heating 
before  compression  produces  some  change,  just  as  increase  of 
temperature  after  compression  produces  change.  The  change  is 

*  Sec  p.  57. 


The  Cause?  of 'Loss  in  Gas  Engines  77 

not  great,  and  it  is  always  in  the  direction  of  improvement  with  a 
limited  expansion.  If  the  lower  temperature  /  is  increased,  the 
compression  temperature  tc  increases  in  proportion,  and  is  ac- 
cordingly nearer  the  maximum  temperature.  The  volume  increases 
less  on  heating,  so  that  the  effect  upon  efficiency  is  the  same  as  if 
the  expansion  had  been  increased  ;  the  terminal  pressure  will  more 
closely  approach  atmosphere,  and  therefore  come  nearer  to  the 
condition  of  maximum  efficiency. 

In  engines  of  type  3  the  compression  and  expansion  are  ofterv 
performed  in  the  same  cylinder.  For  this  purpose  it  is  necessary 
to  leave  at  the  end  of  the  cylinder  a  space  into  which  the  charge 
is  to  be  compressed.  As  the  piston  does  not  enter  this  space,  a 
considerable  volume  of  exhaust  gases  remains  to  mix  with  the  fresh 
cold  charge.  Partly  from  this  and  partly  from  the  heating  effect 
of  the  cylinder  and  piston,  the  charge  becomes  considerably  heated 
before  compression.  The  temperature  of  200°  C.  is  not  unusual. 
Here  the  simplest  case  is  that  where  the  expansion  is  continued 
to  the  same  volume  as  existed  before  compression.  The  efficiency 
depends  solely  upon  the  amount  of  the  compression  ;  for  any 
given  degree  of  compression  it  is  constant,  whether  the  addition 
of  heat  at  constant  volume  after  compression  be  great  or  small. 

The   efficiency  is   E=I  —  '    as  in  type  2  (see  p.  57);  and  the  two 

absolute  temperatures  vary  in  the  same  ratio,  that  is,  if  the  charge 
is  heated  before  compression,  the  temperature  after  compression  will 
be  increased  in  the  same  ratio.  The  two  temperatures  will  therefore 
bear  a  constant  ratio  to  each  other,  whatever  the  initial  temperature 
may  be,  provided  the  compression  is  constant.  Heating  the  charge 
before  compression  will  consequently  have  no  disturbing  effect  upon 
the  theoretical  efficiency.* 

Where  the  expansion  is  carried  to  atmosphere  the  case  is 
different.  The  diagram  (fig.  15)  may  be  considered  to  be  made  up 
of  two  parts  giving  two  different  efficiencies,  the  sum  of  which  in 
this  case  is  0*51.  In  expanding  from  the  compression  volume  v. 
to  the  original  volume  v  (compression  75  Ibs.  per  square  inch) 

*  It  is  here  necessary  to  distinguish  between  theoretical  and  practical  efficiency. 
Heating  before  compression  diminishes  efficiency  in  practice  by  increasing  max- 
imum temperature,  and  therefore  loss  of  heat. 


7  8  The  Gas  Engine 

the  total  efficiency  is  0^37,  and  from  that  volume  to  v  and  atmos- 
pheric pressure,  o'l/j..  The  latter  portion  still  obeys  the  same  law 
as  in  a  similar  case  of  type  i  ;  so  that  if  the  initial  temperature  at 
volume  v  be  supposed  117°  C  it  will  lose  efficiency  in  a  similar 
way.  The  temperature  901°  C.  will  still  exist  at  that  point  of  the 
expanding  line,  so  that  it  may  be  taken  as  similar  to  the  case 
calculated  on  p.  75,  where  1000°  C.  is  the  maximum.  The  loss 
of  efficiency  there  is  from  0*23  to  cri6  for  an  initial  temperature 
of  117°  C.,  which  makes  0*14  become  nearly  o-io.  The  total 
efficiency  would  therefore  be  0-47  instead  of  0*51  without  previous 
heating. 

Efficiency  diminishes  with  increased  temperature  of  working 
fluid  before  compressing,  if  the  expansion  is  carried  to  atmosphere, 
but  does  not  change  where  the  expansion  is  limited  to  the  initial 
volume. 

OTHER  CAUSES  OF  Loss. 

The  third,  fourth,  and  fifth  causes  of  loss  require  for  their  ex- 
amination a  comparison  of  the  actual  diagrams,  and  a  knowledge 
of  the  phenomena  of  explosion  and  combustion,  and  so  cannot  be 
discussed  at  this  stage. 


CHAPTER   V. 

COMBUSTION    AND    EXPLOSION. 

IN  the  preceding  chapters  the  gas  engine  has  been  considered 
simply  as  a  heat  engine  using  air  as  its  working  fluid  ;  it  has  been 
assumed  that  in  the  different  cycles,  the  engineer  is  able  to  give 
the  supply  of  heat  either  instantaneously,  or  slowly,  at  will  ;  and 
also  that  he  can  command  temperatures  so  high  as  1000°  C.  or 
1600°  C.  It  is  now  necessary  to  study  the  properties  of  gaseous 
explosive  mixtures  in  order  to  understand  how  far  these  assump- 
tions are  true. 

ON  TRUE  EXPLOSIVE  MIXTURES. 

•»    V>,     -.','    ,\  -...•;,"<  4     '•, 

When  an  inflammable  gas  is  mixed  with  oxygen  gas  in  certain 
proportions,  the  mixture  is  found  to  be  explosive  :  a  flame  ap- 
proached to  even  a  small  volume  contained  in  a  vessel  open  to  the 
air  will  produce  a  sharp  detonation.  Variation  of  the  proportions 
will  cause  change  in  the  sharpness  of  the  explosion.  There  is  a 
point  where  the  mixture  is  most  explosive  ;  at  that  point  the  in- 
flammable gas  and  the  oxygen  are  present  in  the  quantities 
requisite  for  complete  combination.  After  explosion  the  vessel 
will  contain  the  product  or  products  of  combustion  only,  no 
inflammable  gas  remaining  unconsumed,  or  oxygen  uncombined, 
both  having  quite  disappeared  in  forming  new  chemical  com- 
pounds. 

That  mixture  may  be  called  the  true  explosive  mixture. 

Definition. — When  an  inflammable  gas  is  mixed  with  oxygen 
in  the  proportion  required  for  the  complete  combination  of  both 
gases,  the  mixture  formed  is  the  true  explosive  mixture. 

If  the  chemical  formula  of  an  inflammable  gas  is  known,  the 
volume  of  oxygen  necessary  for  the  true  explosive  mixture  can 


So  The  Ga±  Engine 

be  at  once  calculated.  Elementary  substances  combine  chemi- 
cally with  each  other  in  certain  weights  known  as  the  atomic  or 
combining  weights:  chemical  symbols  are  always  taken  as  repre- 
senting those  weights  of  the  elements  indicated.  In  dealing  with 
inflammable  gases  used  in  the  gas  engine  it  is  convenient  to 
remember  the  following  symbols  and  weights  : 


Element 

Symbol 

Combining  weight 

o 

16 

Hydrogen  
Nitrogen    
Carbon                  ..... 

H 

N 

c 

I 

T4 
1  2 

Sulphur      

s 

32 

In  entering  or  leaving  any  compound  the  elements  invariably 
enter  or  leave  in  weights  proportional  to  those  numbers  or 
multiples  of  them.  Thus  hydrogen  and  oxygen  combine  with 
each  other,  forming  water  ;  the  formula  of  the  compound  is 
H2O,  meaning  that  18  parts  by  weight  contain  16  parts  of  O  and 
2  parts  of  H.  Similarly  when  carbon  combines  with  oxygen  two 
compounds  may  be  formed,  according  to  the  conditions,  carbonic 
oxide  or  carbonic  acid,  formulae  CO  and  CO.2,  the  former  containing 
in  28  parts  by  weight,  12  parts  of  carbon  and  16  parts  of  oxygen ; 
the  latter  in  44  parts  by  weight  containing  12  parts  of  carbon  and 
32  parts  of  oxygen. 

The  formula  of  a  compound  therefore  not  only  indicates  its 
nature  qualitatively,  but  it  also  indicates  its  quantitative  composition. 

H.2O  not  only  tells  the  nature  of  water,  but  it  represents  18 
parts  by  weight ;  CO  means  28  parts  by  weight  of  carbonic  oxide  : 
CO2  means  44  parts  by  weight  of  carbonic  acid.  The  numbers  18, 
28  and  44  are  know  as  the  molecular  weights  of  the  three  com- 
pounds in  question. 

When  dealing  with  gases  it  is  more  convenient  to  think  in 
volumes  than  in  weights.  It  is  easier,  for  instance,  to  measure  the 
proportions  of  explosive  mixtures  by  volume  and  to  say  this  mix- 
ture contains  one  cubic  inch,  one  cubic  foot  or  one  volume  of 
inflammable  gas  to  so  many  cubic  inches,  feet  or  volumes  of  oxygen. 

Fortunately  there  exists  a  simple  relationship  between  the 
volumes  of  elementary  gases  and  their  combining  weights,  and 


Combustion  and  Explosion  Si 

also  between   the   volumes  of  compounds  and    their  molecular 
weights. 

If  equal  volumes  of  the  elementary  gases  are  weighed,  under 
similar  conditions  of  temperature  and  pressure,  it  is  found  that 
their  weights  are  proportional  to  the  combining  weights.  Taking 
the  weight  of  the  hydrogen  as  i,  then  the  weights  of  equal 
volumes  of  nitrogen  and  oxygen  are  14  and  16  respectively.  If 
then  it  is  wished  to  make  a  mixture  of  hydrogen  and  oxygen  gases 
in  the  proportion  of  2  parts  by  weight  of  the  former  to  16  parts  by 
weight  of  the  latter,  it  is  only  necessary  to  take  2  vols.  H  and 

1  vol.  O.     The  law  may  be  stated  in  two  ways,  as  follows  : 

Taking  hydrogen  as  unity  the  specific  gravity  of  the  elementary 
gases  is  the  same  as  their  combining  weights  ;  or 

The  combining  volumes  of  the  elementary  gases  are  equal. 

Instead  of  troubling  to  weigh  out  portions  of  the  gases  it  is 
at  once  known  that  one  volume  of  nitrogen  weighs  14  parts,  the 
same  volume  of  hydrogen  weighing  one  part,  oxygen  16  parts^  and 
so  on  through  all  the  gaseous  elements,  under  the  same  tempera- 
tures and  pressures. 

Knowing  that  water  is  the  compound  formed  by  the  combus- 
tion of  hydrogen  and  oxygen,  and  that  its  formula  is  H2O,  it  is  at 
once  apparent  that  the  true  explosive  mixture  of  these  gases  is 

2  vols.  H  and  i  vol.  O.     By  experiment  it  is  found  that  the  volume 
of  the  water  produced  is  less  (of  course  in  the  gaseous  state)  than 
the  volume  of  the  mixed  gases  before  combination. 

The  measurement  requires  to  be  made  at  a  temperature  hi^h 
enough  to  keep  the  steam  formed  in  the  gaseous  state.  Measure 
2  vols.  H  and  i  vol.  O  into  a  strong  glass  vessel  heated  to  130°  C. ; 
the  total  is  3  vols.  ;  fire  by  the  electric  spark  over  mercury.  It 
will  be  found  that  the  steam  formed  when  it  has  cooled  to  130°  C. 
after  the  explosion,  measures  2  vols.  It  has  been  found  to  be 
true  for  all  gaseous  compounds,  that  however  many  volumes  of 
elementary  gases  combine  to  form  them  the  product  is  always  two 
volumes.  In  elementary  gases,  one  volume  always  contains  the 
combining  weight  ;  in  compound  gases,  two  volumes  always  con- 
tain the  molecular  weight.  Compared  with  hydrogen,  therefore, 
the  specific  gravity  of  a  gaseous  compound  is  always  one-half  of 
the  molecular  weight. 

G 


82  The  Gas  Engine 

As  before,  the  law  may  be  stated  in  two  ways  : 

Taking  hydrogen  as  unity,  the  specific  gravity  of  a  compound 
gas  is  half  its  molecular  weight ;  or 

The  combining  volume  of  a  compound  gas  is  always  equal  to 
double  that  of  an  elementary  gas. 

These  laws  are  known  as  Gay-Lussac's  laws,  and  form  part  of 
the  very  basis  of  modern  chemistry. 

Using  them,  the  true  explosive  mixtures  by  volume  and  the 
volumes  of  the  products  of  the  combination  can  be  found  for  any 
gas  or  mixture  of  gases,  whether  elementary  or  compound. 

The  inflammable  compound  gases,  used  in  the  gas  engine, 
forming  some  of  the  constituents  of  coal  gas  are  : 


Inflammable  gas                        Formula 

Molecular  weight 

Molecular  vol. 

Marsh  o-as    .         .         .         .            CH4 
Ethylene       .                  .                     C.?H4 
Carbonic  oxide     .         .         .             CO 

16 
28 
28 

2 
2 
2 

Applying  Gay-Lussac's  laws,  the  oxygen  required  for  true 
explosive  mixtures  and  the  volumes  of  the  products  of  combus- 
tion are  as  follows  for  all  the  inflammable  gases  used  in  the  gas 
engine  :  H.o  co2 

Steam.  Carbonic 

acid. 

2  vols.  hydrogen  (H)  require  i  vol.  oxygen  (O)  forming    .         .     2  vols. 

2  vols.  marsh  gas  (CH4)  require  4  vols.  oxygen  (O)  forming     .     4  vols.  2  vcls. 

2  vols.  ethylene  (C2H4)  require  6  vols.  oxygen  (O)  forming       .     4  vols.  4  vols. 

2  vo;s.  carbonic  oxide  (CO)  require  i  vol.  oxygen  (O)  forming  2  vols. 

2  vols.  tetrylene  (C4H8)  require  12  vols.  oxygen  (O)  forming     .     8  vols.  8  vols. 

With  hydrogen  and  oxygen  3  volumes  before  combination 
become  2  volumes  after  combination.  CH4  and  O,  also  C2H4  and 
O,  the  volumes  of  the  products  of  combustion,  are  equal  to  the 
volumes  of  mixture.  With  carbonic  oxide  and  oxygen  3  volumes 
before  become  2  volumes  after  combination. 

ON  INFLAMMABILITY. 

Previous  to  1817,  Sir  Humphry  Davy  made  the  admirable 
researches  which  led  him  to  the  invention  of  the  safety  lamp.  He 
then  made  experiments  upon  different  explosive  mixtures,  and 
found  that  under  certain  conditions  they  lost  the  capability  of 


Combustion  and  Explosion  83 

ignition  by  the  electric  spark.  True  explosive  mixtures,  he  ob- 
served, may  lose  inflammability  in  two  ways  ;  by  the  addition  of 
excess  of  either  ot  the  gases  or  of  any  inert  gas  such  as  nitrogen, 
and  by  rarefaction.  The  hydrogen  explosive  mixture,  if  reduced  to 
one-eighteenth  of  ordinary  atmospheric  pressure,  cannot  be  in- 
flamed by  the  spark.  Heated  to  dull  redness  at  this  pressure  it 
will  recover  its  inflammability  and  the  spark  will  cause  combination. 

One  volume  of  the  mixture  to  which  has  been  added  nine 
volumes  of  oxygen  is  uninflammable,  but  if  the  density  is  increased 
or  the  temperature  raised,  it  recovers  its  inflammability. 

Eight  volumes  of  hydrogen  added,  produces  the  same  effect  as 
the  nine  volumes  of  oxygen,  but  only  one  volume  of  marsh  gas 
or  half  a  volume  of  ethylene  is  required.  The  excess  which  destroys 
inflammability  varies  with  the  temperature,  increasing  with  increase 
of  temperature.  Heating  the  mixture  widens  the  range,  both  of 
dilution  with  excess  or  inert  gas  and  reduction  of  pressure. 

The  point  where  inflammability  ceases  by  diluting  is  very 
abrupt  and  sharply  defined.  The  author  has  found  that  a  coal 
gas  which  will  inflame  by  the  spark  in  a  mixture  of  i  gas  and 
14  air  will  not  inflame  with  15  of  air.  If  the  experiment  be  re- 
peated on  a  warmer  day  it  may  inflame  with  15  of  air,  but  will  not 
with  1 6  air.  As  the  proportion  is  fixed  for  any  given  temperature 
it  will  be  convenient  to  call  that  proportion  for  any  mixture  the 
'  critical  proportion.'  Any  mixture  in  the  critical  proportion  be- 
comes inflammable  by  a  very  small  increase  of  temperature  or 
pressure.  The  exact  limits  of  .dilution  temperature  and  pressure 
have  yet  to  be  discovered. 

Passing  from  any  true  explosive  mixture  by  dilution  to  the 
mixture  in  the  critical  proportion,  the  inflammability  slowly 
diminishes,  the  explosion  becoming  less  and  less  violent,  till  at  last 
no  report  whatever  is  produced,  and  the  progress  of  the  flame  (if 
a  glass  tube  is  -used)  is  easily  followed  by  the  eye. 

In  his  great  work  on  gas  analysis,  Professor  Bunsen  confirms 
Davy's  observations  in  every  particular,  proving  loss  of  inflam- 
mability by  dilution  and  reduction  of  pressure  as  well  as  its 
restoration  by  heating,  increase  of  pressure  and  slight  addition  of 
the  inflammable  gas.  His  work,  however,  was  not  published  till 
1857- 

G  2 


84  The  Gas  Engine 


ON  THE  RATE  OF  FLAME-PROPAGATION. 

The  sharp  explosion  of  a  true  explosive  mixture  is  due  to  the 
very  rapid  rate  at  which  a  flame,  initiated  at  one  point,  travels 
through  the  entire  mass  and  thereby  causes  the  maximum  pressure 
to  be  rapidly  attained.  With  a  diluted  mixture  the  flame  travels 
more  slowly.  Dilution  therefore  diminishes  explosiveness  in  two 
ways— by  increasing  the  time  of  getting  the  highest  pressure  and 
also  by  diminishing  the  highest  pressure  which  can  be  got. 
Professor  Bunsen's  experiments  are  the  earliest  attempts  to 
measure  the  velocity  of  flame  movement  in  explosive  mixtures. 
His  method  is  as  follows  : 

The  explosive  mixture  is  allowed  to  burn  from  a  fine  orifice  of 
known  diameter,  and  the  rate  of  the  current  of  the  issuing  gas 
carefully  regulated  by  diminishing  the  pressure  to  the  point  at 
which  the  flame  passes  back  through  the  orifice  and  inflames  the 
explosive  mixture  below  it.  This  passing  back  of  the  flame  occurs 
when  the  velocity  with  which  the  gaseous  mixtures  issue  from  the 
orifice  is  inappreciably  less  than  the  velocity  with  which  the  in- 
flammation of  the  upper  layers  of  burning  gas  is  propagated  to  the 
lower  and  unignited  layers.  Knowing  then  the  volume  of  mixture 
passing  through  the  orifice  and  its  diameter,  the  rate  of  flow  at 
the  moment  of  back  ignition  is  known.  It  is  identical  with  the  rate 
of  flame  propagation  through  the  mixture. 

Bunsen  made  determinations  for  the  true  explosive  mixtures 
of  hydrogen  and  carbonic  oxide. 

VELOCITY  OF  FLAME  IN  TRUE  EXPLOSIVE  MIXTURES.     (Bunsen.'] 

Hydrogen  mixture  (2  vols.  H  and  i  vol.  O) .         .      34  metres  per  sec. 
Carbonic  oxide  mixture  (i  vol.  CO  and  i  vol.  O)  .       i  metre  per  sec.  nearly. 

The  method  is  a  singularly  simple  and  beautiful  one  and 
answered  thoroughly  for  Professor  Bunsen's  purpose  at  the  time 
he  devised  it.  Several  objections,  however,  may  be  brought  against 
it.  The  mixture  in  issuing  from  the  jet  into  the  air  as  flame, 
becomes  mixed  to  some  extent  with  the  air  and  so  cools  down  ; 
the  metal  plate  also,  pierced  with  the  orifice,  exercises  a  great 
cooling  effect.  If  the  hole  were  made  small  enough  the  flame 
could  not  pass  back  at  all,  however  much  the  flow  is  reduced, 


Combustion  and  Explosion  85 

because  the  heat  would  be  conducted  away  so  rapidly  as  to 
extinguish  the  flame.  This  had  been  shown  by  Davy  in  1817; 
indeed  it  is  the  principle  of  the  safety  lamp.  These  causes  prob- 
ably make  Bunsen's  velocities  too  low.  MM.  Mallard  and  Le 
Chatelier  have  made  velocity  determinations  by  a  method  designed 
to  obviate  those  sources  of  error. 

The  explosive  mixture  is  contained  in  a  long  tube  of  considerable 
diameter,  closed  at  one  end,  open  to  the  atmosphere  at  the  other. 
At  each  end  a  short  rubber  tube  terminates  in  a  cylindrical  space 
closed  by  a  flexible  diaphragm.  A  light  style  is  fixed  upon  the 
diaphragms.  A  drum  revolves  close  to  each  style,  both  drums 
upon  the  same  shaft.  A  tuning  fork,  vibrating  while  the  experi- 
ment is  being  made,  traces  a  sinuous  line  upon  the  drum  and  so 
the  rate  of  revolution  is  known.  The  mixture  is  ignited  at  the 
open  end,  and  the  flame  in  passing  the  lateral  opening  leading  to 
the  first  diaphragm  ignites  the  mixture  there,  and  so  moves  the 
style  and  marks  the  drum;  the  arrival  of  the  flame  is  signalled  at 
the  other  end  in  the  same  way.  The  drums  revolving  together, 
the  distance  between  the  two  style  markings  measured  by  the 
vibration  marks  of  the  tuning  fork  gives  the  time  taken  by  the 
flame  to  move  between  the  two  points.  The  numbers  got  in  this 
way  are  the  rates  of  the  communication  of  the  flame  through  the 
mixture,  back  into  the  tube,  while  the  flame  can  freely  expand  to  the 
air;  when  both  ends  are  closed  the  velocity  is  much  greater.  Then, 
not  only  does  the  flame  spread  from  particle  to  particle  of  the 
explosive  mixture  at  the  rate  due  to  contact  of  the  inflamed  particles 
with  the  uninflamedones,  but  the  expansion  produced  by  the  inflam- 
mation projects  the  flame  mechanically  into  the  other  part  and  so 
produces  an  ignition,  which  does  not  travel  at  a  uniform  rate,  but  at  a 
continually  accelerating  one.  In  the  same  way,  using  the  open  tube 
but  firing  at  the  closed  end,  the  expansion  of  the  first  portion  adds 
to  the  apparent  velocity  of  propagation,  and  projects  the  last 
portion  of  the  mixture  into  the  atmosphere.  The  true  velocity  of 
the  propagation  is  the  rate  at  which  the  flame  proceeds  from  particle 
of  inflamed  mixture  to  uninflamed  particle  by  simple  contact ;  the 
true  velocity  depends  upon  inflammability  alone,  the  rate  under 
other  conditions  depends  also  upon  heat  evolved,  and  therefore 
movement  due  to  expansion,  mechanical  disturbance  of  the  unig- 


86  The  Gas  Engine 

nited  by  the  projection  of  the  ignited  portion  into  its  midst.    These 
conditions  may  vary  much  ;  the  inflammability  remains  constant. 

Mallard  and  Le  Chatelier's  results  for  the  true  velocity  of  pro- 
pagations are  : 

VELOCITY  OF  FLAME  IN  TRUE  EXPLOSIVE  MIXTURES. 
(Mallard  and  Le  Chatelier. } 

per  sec. 

Hydrogen  mixture  (2  vols.  H  and  i  vol.  O)   .         .         .20  metres. 
Carbonic  oxide  (2  vols.  CO  and  i  vol.  O)      .         .         .     2'2     ,, 

Bunsen's  rate  for  hydrogen  mixture  seems  to  have  been  too 
great,  and  for  carbonic  oxide  mixture  too  little.  The  rate  for  a  true 
and  very  explosive  mixture  such  as  hydrogen  is  liable  to  be  inac- 
curately determined,  as  temperature  variation  makes  a  great 
change,  and  it  is  difficult  even  with  Mallard  and  Le  Chatelier's 
method  to  obtain  concordant  experiments.  With  less  inflammable 
mixtures  the  difficulty  disappears.  As  true  explosive  mixtures  are 
never  used  in  the  gas  engine,  their  properties  concern  the  engineer 
only  as  a  preliminary  to  the  study  of  diluted  mixtures.  The  most 
explosive  mixture  which  can  be  made  with  air  contains  a  large 
volume  of  nitrogen  inevitably  present  as  diluent. 

The  following  are  some  of  their  results  with  diluted  mixtures, 
which  are  stated  to  be  correct  within  10  per  cent,  error  of  experi- 
ment : 
VELOCITY  OF  FLAME  IN  DILUTED  MIXTURES.     (Mallard  and  Le  Chatelier.') 

per  sec. 

i  vol.  hydrogen  mixture  +  \.  vol.  oxygen         .         „         .     17-3  metres, 
i,  ,,  +i  vol.  oxygen        .         .          .10          ,, 

+  i  vol.  hydrogen  .     18 

+  i  vol.  hydrogen    .         .         .11*9      ,, 
+  2  vols.  hydrogen .         .  8'i      ,, 

These  rates  show  that  the  true  explosive  mixture  of  hydrogen 
and  oxygen  when  diluted  with  its  own  volume  of  oxygen  falls  from 
20  metres  per  second  to  10  metres,  that  is,  it  becomes  one-half 
as  inflammable  ;  when  its  own  volume  of  hydrogen  is  the  diluent, 
the  velocity  only  falls  to  11-9  metres  per  second.  Hydrogen  there- 
fore has  less  effect  in  diminishing  inflammability  than  oxygen. 

Remembering  the  fact  that  the  atmosphere  contains  one-fifth 
of  its  volume  of  oxygen,  the  remaining  four-fifths  being  nearly  all 
nitrogen,  it  is  easy  to  get  the  proportions  for  the  strongest  explosive 


Combustion  and  Explosion  87 

mixture  possible  with  air.    Two  volumes  hydrogen  require  i  volume 
oxygen,  and  therefore  5  volumes  air.  The  strongest  possible  mixture 
with  air  is  two-sevenths  hydrogen,  five-sevenths  air.  The  following 
experiments  are  for  hydrogen  and  air  in  different  proportions  : 
VELOCITY  OF  FLAME  IN  DILUTED  MIXTURES.     (Mallard  and  Le  Ckatclier.} 


Mixture, 


per  sec 


vol.  H  and  4  vols.  air  .  ...  2     metres. 

,,  H  and  3  vols.  air  .  .         .  2 '8  ,, 

,,  H  and  2j  vols.  air  .  .         .         •  3*4  n 

,,  H  and  if  vols.  air  .  .         .         .  4-1  „ 

,,  H  and  i£  vols.  air  .  .         ,  4-4  ,, 

i    „  H  and  i  vol.  air  ....  3-8 

,,       i    ,,  H  and  ^  vol.  air  .  .         .         .  2-3  ,, 

Very  strangely  the  velocity  is  greatest  when  there  is  an  excess 
of  hydrogen  present.  To  get  just  enough  of  oxygen  for  complete 
burning  i  volume  H  requires  2\  volumes  air,  which  would  be 
naturally  supposed  to  be  the  most  inflammable  mixture,  as  it  gives 
out  the  greatest  heat,  but  for  some  reason  it  is  not.  When  the 
hydrogen  is  increased  beyond  that  point  the  velocity  again  falls  off. 
A  determination  for  coal  gas  and  air  gave  i  volume  gas.  5 
volumes  air  a  velocity  of  i'oi  metres  per  second,  and  i  volume  gas, 
6  volumes  air  0*285  metres  per  second.  With  coal  gas  also  the 
maximum  velocity  is  got  with  the  gas  slightly  in  excess. 

So  far,  these  rates  of  ignition  or  inflammation  are  measures  of 
inflammability,  and  are  the  rates  for  constant  pressure;  the  rates  for 
constant  volume  are  very  different,  and  the  problem  is  a  more 
complex  one.  Inflaming  at  the  closed  end  of  the  tube,  they  found 
that  even  very  dilute  mixtures  gave  a  sharp  explosion,  and  in  the 
case  of  hydrogen  true  explosive  mixture,  the  velocity  became  1000 
metres  per  second  instead  of  20.  With  hydrogen  and  air  300 
metres  per  second  were  obtained. 

MM.  Berthelot  and  Vieille  have  proved  that  under  certain  con- 
ditions even  greater  velocities  than  these  are  possible.  The  con- 
ditions, however,  are  abnormal,  and  the  generation  of  M,  Berthelot's 
explosive  wave  is  exceedingly  undesirable  in  a  gas  engine.  It  is 
generated  by  inflaming  a  considerable  portion  of  the  mixture  at 
once,  and  so  causing  the  transmission  of  a  shock  from  molecule 
to  molecule  of  the  uninflamed  mixture:  this  shock  causes  an 
ignition  velocity  nearly  as  rapid  as  the  actual  mean  velocity  of 
movement  of  the  gaseous  molecules  at  the  high  temperatures  of 


88  The  Gas  Engine 

combustion.  The  difference  between  this  almost  instantaneous 
detonation  and  the  ordinary  flame  propagation  may  be  compared 
to  similar  differences  in  the  explosion  of  gun  cotton  discovered 
by  Sir  Frederic  Abel.  Gun  cotton  lying  loosely,  and  open  to  the 
air,  will  burn  harmlessly  if  ignited  by  a  flame;  indeed,  a  consider- 
able portion  may  be  laid  upon  the  open  hand  and  ignited  by  a 
flame  without  the  smallest  danger.  The  same  quantity  in  the 
same  position,  if  fired  by  a  percussive  detonator,  will  occasion 
the  most  violent  explosion,  the  nature  of  the  shock  given  to  the 
gun  cotton  by  the  detonator  causing  a  transmission  of  the  kind  of 
vibration  necessary  to  cause  its  almost  instantaneous  resolution 
into  its  component  gases. 

The  explosive  wave  in  gases  seems  to  originate  in  like  con- 
ditions. Its  velocity  for  the  true  explosive  mixture  of  hydrogen 
and  oxygen  is  2841  metres  per  second,  and  for  carbonic  oxide 
mixture,  1089  metres  per  second.  The  velocity  is  independent  of 
pressure  between  half  an  atmosphere  and  one  and  a  half  atmo- 
sphere. It  is  independent,  too,  of  the  diameter  of  the  tube  used, 
within  considerable  limits,  or  of  the  material  of  the  tube,  rubber 
and  lead  tubes  giving  similar  results.  Diluting  the  mixtures  di- 
minishes, and  heating  increases  it.  The  experiments  are  very 
interesting  and  important,  from  a  physicist's  standpoint,  but, 
fortunately  for  the  inventor  dealing  with  gas  engines,  the  explosive 
wave  is  not  easily  generated  in  a  gas  engine  cylinder;  if  it  were, 
it  would  be  impossible  to  run  the  engines  without  shock  and 
hammering.  ' 

The  velocity  which  really  concerns  the  engineer  is  that  due 
to  inflammability,  and  expansion  produced  by  inflaming — the 
velocity,  in  fact,  with  which  the  inflammation  spreads  through  a 
closed  vessel.  As  it  cannot  be  discussed  without  considering 
other  matters — heat  evolved  by  combustion,  and  temperatures  and 
pressures  produced — it  will  be  advisable  first  to  give  the  heat 
evolved  by  combustion,  and  then  devote  a  complete  chapter  to 
explosion  in  a  closed  vessel. 

HEAT  EVOLVED  BY  COMBUSTION. 

Careful  experiments  upon  the  heat  evolved  by  the  combustion 
of  gases  in  oxygen  have  been  made  by  Favre  and  Silberman,  and 


Combustion  and  Explosion  89 

also  by  Professor  Andrews.  The  physicists  first  named  burned 
the  gases  at  constant  pressure  in  a  specially  devised  calorimeter. 
Professor  Andrews  mixed  the  gases  in  a  thin  spherical  copper 
vessel,  closed  it,  and  exploded  by  the  spark:  the  vessel  being  sur- 
rounded by  water  gave  up  its  heat  to  the  water,  the  weight  of  which 
being  known,  the  rise  of  temperature  gave  the  heat  evolved. 

Quantities  of  heat  are  measured  by  taking  water  as  the  unit. 
In  this  work,  a  heat  unit  always  means  the  amount  of  heat  neces- 
sary to  raise  unit  weight  of  water  through  i°  C. 

Taking  an  average  of  Favre  and  Silberman  and  Andrews's 
results,  the  inflammable  gases  used  in  gas  engines  evolve  upon  com- 
plete combustion  the  following  amounts  of  heat  : 

Heat  units. 

Unit  weight  of  hydrogen  completely  burned  to  HoO  evolves  .  .  34,170 
Unit  weight  of  carbon  completely  burned  to  COo  evolves  .  .  .  8,000 
Unit  weight  of  carbonic  oxide  completely  burned  to  CO2  evolves  .  2,400 
Unit  weight  of  marsh  gas  completely  burned  to  COo  and  H.>O  evolves  13,080 
Unit  weight  of  ethylene  completely  burned  to  CO.2  and  H.^O  evolves  11,900 

That  is,  one  pound  weight  of  hydrogen  burned  completely  to 
water  will  evolve  as  much  heat  as  would  raise  34,170  Ibs.  of  water 
through  i°  C.,  or  the  converse.  One  pound  of  carbon  in  burning 
to  carbonic  acid  evolves  as  much  heat  as  would  raise  8,000  Ibs.  of 
water  through  i°  C.  These  numbers  give  the  amount  or  quantity 
of  heat  evolved.  The  intensity  or  temperature  of  the  combustion 
-maybe  calculated  on  the  assumption  that  the  whole  heat  is  evolved 
under  such  conditions  that  no  heat  is  lost,  or  is  applied  to  any- 
thing else  but  the  products  of  combustion.  To  make  the  calcu- 
lation it  is  necessary  to  know  the  specific  heat  of  the  products. 

The  amount  of  heat  required  to  heat  unit  weight  of  water 
through  one  degree  is  i  heat  unit,  the  specific  heat  of  any  other 
body  is  the  number  of  heat  units  required  to  heat  unit  weight  of  the 
body  through  one  degree.  Gases  have  two  different  specific  heats 
depending  upon  whether  heat  is  applied  while  the  gas  is  kept  at  con- 
stant volume,  or  at  constant  pressure;  both  are  required  in  dealing 
with  gas  engine  problems.  The  specific  heat  at  constant  volume 
is  sometimes  known  as  the  true  specific  heat;  in  taking  the  specific 
heat  at  constant  pressure  the  gas  necessarily  expands,  and  so  does 
work  on  the  external  air;  this  specific  heat  is  therefore  greater 
than  the  former  by  the  amount  of  work  done.  For  the  gases  used 


The  Gas  Engine 


in  the  gas  engine  the  two  values  are  as  follows.  The  ratio  be- 
tween the  two  is  also  given,  as  it  is  frequently  required  in  efficiency 
calculations.  The  experimental  numbers  are  Regnault's,  the 
calculated  specific  heat  at  constant  volume,  Clausius. 


SPECIFIC  HEATS  OF  GASES. 
(For  equal  weights.      Water  =  i.) 


Name  of  gas 

Sp.  heat  at 
constant  pressure 

Sp.  heat  at 
constant  volume 

Sp.  heat  con.  pres. 
Sp.  heat  con.  vol. 

Air 

0-237 

O'l68 

•413 

Oxvgen 

0-217 

Q'i55 

•403 

Nitrogen 

0-244 

0-173 

•409 

Hydrogen 

3  '409 

2-406 

•417 

Marsh  gas 

o'593 

0-467 

— 

Ethvlene 

0-404 

0-332 

•144 

Carbonic  oxide 

0-245 

0-173 

•416 

Steam    . 

0-480 

0-369 

•502 

Carbonic  acid 

0'2l6 

0-171 

•I6S 

It  is  convenient  to  remember  that  the  specific  heats  of  com- 
bining or  atomic  weights  of  the  elements  are  equal  —  Dulong  and 
Petit's  law.  To  this  law  there  are  few  exceptions,  and  the  per- 
manent elementary  gases,  oxygen,  nitrogen,  and  hydrogen,  obey  it 
almost  absolutely.  As  equal  volumes  of  these  gases  represent  the 
combining  weights,  it  follows  that  equal  volumes  of  these  gases 
have  the  same  specific  heat.  Taking  the  specific  heat  of  air  as 
the  unit,  the  specific  heat  of  hydrogen  and  oxygen  gases  is  also 
unity.  The  compound  gases  do  not  obey  the  law  so  closely. 
The  calculation  of  temperature  of  combustion  can  now  be  made. 
The  amount  of  heat  evolved  from  unit  weight  of  a  combustible  is 
usually  said  to  measure  its  calorific  power,  that  amount  divided  by 
the  specific  heat  of  the  products  of  the  combustion  is  said  to  be  the 
measure  of  its  calorific  intensity.  The  calorific  intensity  is  indeed 
the  theoretical  temperature  of  the  combustion  :  taking  hydrogen 
first,  unit  weight  evolves  34,170  heat  units.  But  the  water  formed 
weighs  9  units  (from  formula  H2O),  and  if  its  specific  heat  in  the 
gaseous  state  were  unity,  the  supposed  maximum  temperature  of 


combustion  would  be   ^1I°  =  3796-6.     But  the  specific  heat  is 


^^^^ 

Combustion  and  Explosion  91 

less  than  unity  ;  therefore  the  theoretical  maximum  will  be  greater. 

It  is  —  34  !  7°      _  79097.     For  certain  reasons  to  be  considered 
9  x  0*400 

later,  no  such  enormous  temperatures  are  ever  attained  by  com- 
bustion. In  the  above  calculation  the  latent  heat  of  steam  should 
first  have  been  deducted,  as  it  is  included  in  the  total  heat  evolved 
as  measured  by  the  calorimeter  :  it  is  537  heat  units.  34,170  —  537 
gives  the  total  heat  available  for  increasing  the  temperature,  the 


amended  calculation  is    ^i__  —        =7  785  '4,  still  an  exceedingly 
9  x  o'4oo 

high  temperature. 

Calculating  the  heat  evolved  by  burning  carbon  in  the  same 
way,  but  omitting  any  deduction  for  the  latent  heat  of  carbonic 
acid  (it  does  not  affect  the  calorimeter,  as  it  does  not  condense), 
the  theoretical  temperature  produced  by  burning  in  oxygen  is 
still  higher,  being  10,174°  C.  Burning  in  air  the  theoretical 
temperatures  are  lower  as  the  nitrogen  present  acts  as  a  diluent, 
and  must  necessarily  be  heated  to  the  same  temperature  as  the 
products  of  the  combustion.  They  are  given  as  follows  in  '  Watts' 
Dictionary.' 

Temperature  produced 
Calorific  power          -  -          ----  ^ 

In  oxygen          In  air 

Carbcn     .  .  .^  .   „    .,.,-'....  8080          10174°  C.  27*      C. 

Hydrogen      ....         34462  6930°  C.  2741°  C. 

These  are  the  supposed  temperatures  burning  in  the  open 
atmosphere,  and  therefore  at  constant  pressure,  the  gases  expand- 
ing doing  work  upon  the  air.  At  constant  volume,  that  is, 
burning  in  a  closed  vessel  so  that  the  volume  cannot  increase  but 
onlf  the  pressure,  the  temperature  should  be  greater  as  the 
specific  heat  at  constant  volume  is  less.  Allowing  for  that,  the 
numbers  become 

THEORETICAL  TEMPS.  OF  COMBUSTION  AT  CONSTANT  VOLUME. 

Temperature  produced 

In  oxygen       In  air 

Carbon       ....         12820 
Hydrogen  .         ...  9010  4119 

Such  temperatures  have  never  been  produced  by  combustion, 


92  The  Gas  Engine 

for  many  reasons,  of  which  all  save  the  most  potent  have  been 
discussed  by  the  earlier  writers  on  heat.     This  is  Dissociation. 


DISSOCIATION. 

Most  chemical  combinations,  while  in  the  act  of  formation 
from  their  constituent  elements,  evolve  heat,  and  as  a  general 
rule,  the  greater  the  heat  evolved  the  more  stable  is  the  com- 
pound formed.  The  compound  after  formation  may  generally  be 
decomposed  by  heating  to  a  high  enough  temperature,  heat  being 
one  of  the  most  powerful  splitting  up  agencies  known  to  the  chemist. 
The  nature  of  the  decomposition  varies  with  the  compound.  In 
many  cases  the  process  is  irreversible,  that  is,  although  heating  up 
\\ill  cause  decomposition,  cooling  down  again,  however  slowly, 
will  not  cause  recombination.  In  some  compounds,  however,  under 
certain  conditions  the  process  is  reversible,  and  recombination 
occurs  on  slow  cooling. 

Definition.— Dissociation  may  be  defined  as  a  chemical 
decomposition  by  the  agency  of  heat,  occurring  under  such  con- 
ditions that  upon  lowering  the  temperature  the  constituents 
recombine. 

Groves  found  long  ago  that  water  begins  to  split  up  into 
oxygen  and  hydrogen  gases  at  temperatures  low  compared  to  that 
produced  by  combustion.  Deville  made  a  careful  study  of  the 
phenomena,  and  found  that  decomposition  commences  at  960°  to 
1000°  C.  and  proceeds  to  a  limited  extent  :  raising  the  temperature 
to  1200°  C.  increases  it,  but  a  limit  is  reached.  The  amount  of 
decomposition  depending  upon  the  temperature,  for  each  tempe- 
rature there  is  a  certain  proportion  between  the  amount  of  steam 
and  the  amount  of  free  oxygen  and  hydrogen  gases  present.  If 
the  temperature  is  increased,  the  proportion  of  free  gases  also 
increases  :  if  temperature  is  diminished,  the  proportion  of  free 
gases  diminishes.  If  the  temperature  be  raised  beyond  a  certain 
intensity,  the  water  is  completely  decomposed  :  if  lowered  beyond 
a  certain  temperature,  complete  combination  results.  The  same 
thing  happens  with  carbonic  acid,  the  temperature  of  decomposition 
is  lower. 

It  is  quite  evident,  then,  that  at  the  highest  temperatures  pro- 


Combustion  and  Explosion  93 

duced  by  combustion,  the  product  cannot  exist  in  the  state  of 
complete  combination.  It  will  be  mixed  to  a  certain  extent  with 
the  free  constituents  which  cannot  combine  further  until  the  tem- 
perature falls;  as  the  temperature  falls,  combustion  will  continue 
till  all  the  free  gases  are  combined.  The  subject,  from  its  nature, 
is  a  difficult  one  in  experiment,  and  accordingly  different  observers 
do  not  quite  agree  upon  temperatures  and  percentages  of  dissocia- 
tion, but  all  are  agreed  that  dissociation  places  a  rigid  barrier  in 
the  way  of  combustion  at  high  temperatures,  and  prevents  the 
attainment  of  temperatures,  by  combustion,  which  are  otherwise 
quite  possible.  With  no  dissociation,  hydrogen  burning  in  oxygen 
should  be  able  under  favourable  circumstances  to  give  a  tempera- 
ture of  over  6000°  C,  as  has  been  shown.  Deville's  experiments 
upon  the  temperature  of  the  oxyhydrogen  flame,  at  constant 
pressure  of  the  atmosphere,  gave  under  2500°  C.  The  estimate 
was  made  by  melting  platinum  in  a  lime  crucible,  with  the  oxy- 
hydrogen flame  playing  upon  the  platinum,  the  crucible  being 
well  protected  against  loss  of  heat  by  lime  blocks,  so  that  the 
platinum  could  really  attain  the  temperature  of  the  flame;  when 
at  the  highest  temperature,  the  molten  platinum  was  rapidly 
poured  into  a  weighed  calorimeter,  and  the  rise  in  temperature 
noted.  From  this  was  calculated  the  temperature  of  the  platinum. 
The  experiment  was  dangerous  and  inaccurate,  but  it  is  the  only 
serious  attempt  which  has  been  made  to  determine  the  temperature 
of  the  oxyhydrogen  flame  at  constant  pressure. 

The  highest  temperature  produced  by  hydrogen  burning  in 
oxygen  has  been  determined  by  Bunsen,  and  also  Mallard  and 
Le  Chatelier,  for  combustion  at  constant  volume,  that  is,  ex- 
plosion. 

As  the  theoretic  calculation  shows,  with  no  dissociation  a 
temperature  of  9000°  C.  is  possible.  The  highest  maximum  it 
is  possible  to  assume  from  Bunsen's  experiments  is  3800°  C.  ; 
from  Mallard  and  Le  Chatelier's,  3500°  C.  The  two  sets  of  ex- 
periments are  concordant.  It  is  true  the  latter  physicists  do  not 
attribute  the  difference  wholly  to  dissociation,  but  they  agree  that 
part  is  due  to  this  cause;  and  that  there  is  an  enormous  difference 
between  heat  temperature  actually  got  and  that  which  should  be 
possible  if  no  limit  existed  all  are  agreed.  With  air,  Bunsen's 


94  The  Gc,s  Engine 

figures  show  a  maximum  of  about  2000°  C,  Mallard  and  Le 
Chatelier  say  1830°  C.;  the  present  writer  has  also  made  experi- 
ments with  hydrogen  in  air,  and  finds  the  highest  possible  tem- 
perature to  be  1900°  C.  The  calculated  maximum  is  3800°  C. 
The  difference  is  not  so  great  as  with  the  true  explosive  mixture, 
which  is  to  be  expected,  but  all  experiments  agree  in  proving  that 
there  is  a  considerable  difference. 


95 


CHAPTER  VI. 

EXPLOSION    IN    A    CLOSED    VESSEL. 

THE  value  of  any  inflammable  gas  for  the  production  of  power 
by  explosion,  can  be  determined  apart  altogether  from  theoretical 
considerations  by  direct  experiment.  It  is  evident  that  the  gas 
which  for  a  given  volume  causes  the  greatest  increase  in  pressure, 
will  give  the  greatest  power  for  every  cubic  foot  used,  provided 
that  the  pressure  does  not  fall  so  suddenly  that  it  is  gone  before  it 
can  be  utilised  by  the  piston. 

Two  qualities  will  be  possessed  by  the  best  explosive  mixture  : 
(i)  greatest  pressure  per  unit  volume  of  gas:  (2)  longest  time  of 
maximum  pressure  when  exposed  to  cooling. 

In  the  gas  engine  itself  the  conditions  are  so  complex  that  the 
problem  is  best  studied  in  the  first  instance  under  simplified  con- 
ditions. The  author  has  made  a  set  of  experiments  upon  many 
samples  of  coal  gas  mixed  with  air  in  varying  proportions,  to  find 
the  pressures  produced,  and  the  duration  of  those  pressures; 
igniting  mixtures  at  atmospheric  pressures  and  temperature,  and 
also  at  higher  temperature  and  initial  pressures.  He  has  made 
some  experiments  upon  pure  hydrogen  and  air  mixtures  in  the 
same  apparatus  for  comparison. 

The  experimental  apparatus  is  shown  at  fig.  19.  It  consists  of 
a  closed  cylindrical  vessel  7  inches  diameter  and  8|  inches  long, 
internal  measurement,  and  therefore  of  317  cubic  inches  capacity. 
It  is  truly  bored,  and  the  end  covers  turned  so  that  the  internal 
surface  is  similar  to  that  of  an  engine  cylinder  ;  the  covers  are 
bolted  strongly  so  as  to  withstand  high  pressures.  Upon  the 
upper  cover  is  placed  a  Richards  indicator,  in  which  the  reci- 
procating drum  has  been  replaced  by  arevolvingone;  the  rate  of  re- 
volution is  adjustedby  a  small  fan,  a  weight  and  gear  givingthe  power. 


gfi  The  Gas  Engine 

The  cylinder  is  filled  with  the  explosive  mixture  to  be  tested; 
the  drum  is  set  revolving,  the  pencil  of  the  indicator  pressed 
gently  against  it,  and  the  electric  spark  is  passed  between  the 
points  placed  at  the  bottom  of  the  space.  The  drum  is  enamelled 
and  the  pencil  is  a  black-lead  one.  The  pressure  of  the  explo- 


REVOLVING  DRUM 


WEIGHT 


FIG.  19.— Clerk  Explosion  Apparatus. 

tion  acts  upon  the  indicator  piston,  and  a  line  is  traced  upon  the 
drum,  which  shows  the  rise  and  fall  of  pressure.  The  rising  line 
traces  the  progress  of  the  explosion  ;  the  falling  line  the  progress 
of  the  loss  of  pressure  by  cooling.  The  rate  of  the  revolution  of 
the  drum  being  known,  the  interval  of  time  elapsing  between  any 
two  points  of  the  explosion  or  cooling  curve  is  also  known.  That 
is,  the  curve  shows  the  maximum  pressure  attained,  the  time  of 
attaining  it,  and  the  time  of  cooling.  Line  b  on  fig.  20  is  a  fac- 


Explosion  in  a  Closed  Vessel 


simile  of  the  curve  produced  by  the  explosion  of  a  mixture  con- 
taining i  vol.  hydrogen  and  4  vols.  air.  Each  revolution  of  the 
drum  was  accomplished  in  0-33  sec.,  so  that  each  tenth  of  a  revolu- 
tion takes  0-033  sec.  The  vertical 
divisions  give  time;  the  horizontal, 
pressures.  In  this  experiment  the 
maximum  pressure  produced  by  the 
explosion  is  68  Ibs.  per  square  inch 
above  atmosphere,  and  it  is  attained 
in  0-026  second.'  Compared  with 
the  rate  of  increase  the  subsequent 
fall  is  very  slow.  The  rise  occurs  in 
0*026  second;  the  fall  to  atmo- 
sphere again  takes  1*5  second,  or 
nearly  sixty  times  the  -other.  It  is 
in  fact  an  indicator  diagram  from  an 
explosion  where  the  volume  is  con- 
stant, the  motor  piston  being  absent, 
and  the  only  cause  of  loss  of  pres- 
sure is  cooling  by  the  enclosing 
walls.  The  exact  composition  of 
the  mixture,  its  uniform  admixture, 
the  temperature  and  pressure  before 
ignition,  are  all  accurately  known. 
After  studying  explosions  under 
these  known  conditions,  it  becomes 
easier  to  understand  what  occurs 
under  more  complex  conditions, 
where  the  moving  piston  makes  the 
cooling  surface  change,  and  where  the 
expansion  doing  work  also  requires 
consideration.  As  the  rapidity 
of  the  increase  of  pressure  measures 
the  explosiveness  of  a  mixture,  the 
time  occupied  from  the  commence- 
ment of  increase  to  maximum  pres- 
sure will  be  called  the  time  of  explosion.  The  explosion  is  com- 
plete when  maximum  pressure  is  attained.  It  does  not  follow  from 

H 


ipui  -bs  jad  -sq[  ui 


The  Gas  Engine 


tpui  'bs  jsi  -sqj  ui 


Explosion  in  a  Closed  Vessel 


99 


this  that  the  combustion  is  complete;  that  is  another  matter.  The 
explosion  arises  from  the  rapid  spreading  of  the  flame  throughout  the 
whole  mass  of  the  mixture,  which  may  be  called  the  inflammation  of 
the  mixture.  More  or  less  rapid  inflammation  means  more  or 
less  explosive  effect,  but  not  complete  combustion.  The  complete 
burning  of  the  gases  present  does  not  occur  till  long  after  com- 
plete 'inflammation. 

The  terms  combustion,  explosion,  and  inflammation  will  be  used 
in  this  sense  alone  : 

Combustion,  burning ;  complete  combustion,  the  complete 
burning  of  the  carbon  of  the  combustible  gas  to  carbonic  acid,  and 
the  hydrogen  to  water.  So  long  as  any  portion  of  the  combustible 
remains  uncombined  with  oxygen  the  combustion  is  incomplete. 

Complete  explosion,  the  attainment  of  maximum  pressure. 

Time  of  explosion;  the  time  elapsing  between  beginning  of 
increase  and  maximum  pressure. 

Complete  inflammation,  the  complete  spreading  of  the  flame 
throughout  the  mass  of  the  mixture. 

Confusion  has  arisen  through  the  indifferent  use  of  these  terms, 
which  are  really  distinct  and  are  not  synonymous. 

With  mixtures  made  with  Glasgow  coal  gas  the  author  has 
obtained  the  following  maximum  pressures  and  times  of  explosion. 

EXPLOSION  IN  A  CLOSED  VESSEL.     (Clerk.} 

Mixtures  of  air  and  Glasgow  coal  gas. 
Temp,  before  explosion      .         ......         .         .     18°  C. 

Pressure  before  explosion  .         .  V.         .         ..     atmospheric. 


Mixture 

Max.  press,  above  atmos. 
in  pounds  per  sq.  in. 

Time  of  explosion 

Gas. 

Air. 

vol. 

13  vols. 

52 

0-28  sec. 

vol. 

ii  vols. 

63 

o'i8  sec. 

vol. 

9  vols. 

69 

0-13  sec. 

vol. 

7  vols. 

89 

0*07  sec. 

vol. 

5  vols. 

96 

6-05  sec. 

The  highest  pressure  which  any  mixture  or  coal  gas  and  air 
is  capable  of  producing  without  compression  is  only  96  Ibs.  per 
sq.  in.  above  atmosphere  and  the  most  rapid  increase  is  not  more 
rapid  than  always  occurs  in  a  steam  cylinder  at  admission.  Many 


IOO 


The  Gas  Engine 


are  still  prejudiced  against  gas,  compared  with  steam,  because  of 
the  so-called  explosive  effect,  and  the  fear  that  gas  explosions 
may  occasion  pressures  quite  beyond  control,  like  solid  explosives. 
The  fear  is  quite  unfounded  ;  the  pressure  produced  by  the 
strongest  possible  mixture  of  coal  gas  and  air  is  strictly  limited 
by  the  pressure  before  ignition,and  can  always  be  accurately  known ; 
and  so  provided  for  by  a  proper  margin  of  safety  in  the  cylinders 
and  other  parts  subject  to  it. 

The  most  dilute  mixture  of  air  and  Glasgow  gas  which  can  be 
ignited  at  atmospheric  pressure  and  temperature  contains  T\-  of 
its  volume  of  gas,  and  the  pressure  produced  is  52  Ibs.  above 
atmosphere.  The  time  of  explosion  is  0*28  second;  so  slow  is 
the  rise  that  it  cannot  with  justice  be  termed  an  explosion.  It  is 
too  slow  to  be  of  any  use  in  an  engine  running  at  any  reasonable 
speed  ;  the  stroke  would  be  almost  complete  before  the  pressure 
had  risen.  The  mixture  containing  6  volumes  of  gas  is  that 
with  just  enough  oxygen  to  burn  the  gas.  It  is  anomalous  that 
the  highest  pressure  is  given  with  excess  of  coal  gas.  The  rate  of 
ignition  also  is  greatest  with  that  mixture.  This  agrees  with  the 
results  obtained  by  Mallard  and  Le  Chatelier,  excess  of  hydrogen 
giving  the  highest  rate  of  inflammation. 

Similar  experiments  were  made  with  air  and  Oldham  coal  gas. 

EXPLOSION  IN  A  CLOSED  VESSEL.     (Clerk.) 

Mixtures  of  air  and  Oldham  coal  gas. 

Temp,  before  explosion         .         .                  .         .         .     17°  C. 
Pressure  before  explosion atmospheric. 


Mixture 

Max.  press,  above  atmos. 
in  pounds  per  sq.  in. 

Time  of  explosion 

Gas. 

Air. 

vol. 

14  vols. 

40 

0-45  sec. 

vol. 

13  vols. 

SI'S 

0*31  sec. 

vol. 

12  VOls. 

60 

o'24  sec. 

vol. 

ii  vols. 

61 

o'i7  sec. 

vol. 

9  vols. 

78 

o'o8  sec. 

vol. 

7  vols. 

87 

o'o6  sec. 

vol. 

6  vols. 

9° 

o'04  sec. 

vol. 

5  vols. 

9i 

°'°55  sec- 

vol. 

4  vols. 

80 

0*16  sec. 

The  highest  pressure  in  this  case  is  91  Ibs.  per  square  inch 


Explosion  in  a  Closed  Vescel 


101 


above  atmosphere,  but  the  most  rapid  explosion  is  0*04  second 
and  90  Ibs.  pressure,  a  little  less  pressure  than  is  given  by  Glasgow 
gas  but  a  slightly  more  rapid  ignition.  The  mixtures  are  evidently 
more  inflammable,  as  the  critical  mixture  is  T13-  volume  of  gas 
instead  of  TJT  as  with  Glasgow  gas.  Although  repeatedly  tried, 
a  mixture  of  i  volume  gas  15  volumes  air  failed  to  inflame  with 
the  spark. 

Hydrogen  and  air  mixtures  were  also  tested  as  follows : 

EXPLOSION  IN  A  CLOSED  VESSEL.     (Clerk.} 
Mixtures  of  air  and  hydrogen. 

Temp,  before  explosion 16°  C. 

Pressure  before  explosion atmospheric. 


Mixture 

Max.  press,  above  atmos. 
in  pounds  per  sq.  in. 

Time  of  explosion 

Hyd. 

Air. 

i  vol. 

6  vols. 

41 

0-15  sec. 

i  vol. 

4  vols. 

68 

0-026  sec. 

2  VOlS. 

5  vols. 

80 

o'oi  sec. 

The  inferiority  of  hydrogen  to  coal  gas,  volume  for  volume,  is 
very  evident ;  the  highest  pressure  is  only  80  Ibs.  above  atmosphere, 
and  the  mixture  requires  f  of  its  volume  of  hydrogen  to  give  it, 
while  coal  gas  gives  the  same  pressure  with  about  T^  volume.  The 
hydrogen  mixture,  too,  ignites  so  rapidly  that  it  would  occasion 
shock  in  practice,  the  strongest  mixture  having  an  explosion  time 
of  one-hundredth  of  a  second.  With  gas  the  most  rapid  is  four- 
hundredths  of  a  second. 


THE  BEST  MIXTURE  FOR  USE  IN  NON-COMPRESSION  ENGINES. 

From  these  tables  can  be  ascertained  the  best  gas  and  the  best 
mixture  for  use  in  non-compression  engines  with  cylinders  kept 
cold-  Take  first  Glasgow  gas,  and  determine  which,  mixture  gives 
the  best  result. 

(i)  Power  of  producing  pressure. 

Suppose  one  cubic  inch  of  Glasgow  coal  gas  to  be  used  in  each  of 
the  five  mixtures,  whose  maximum  pressures  and  times  of  explo- 
sion are  given  in  the  table  on  p.  99,  the  mixtures  would  measure 


IO2  The  Gas  Engine 

respectively  14,  12,  10,  8,  and  6  cubic  inches.  Let  them  be  placed 
in  cylinders  of  14,  12,  10,  8  and  6  square  inches  piston  area  ;  the 
piston  will  in  each  case  be  raised  one  inch  from  the  bottom  of  its 
cylinder.  If  the  pressures  upon  the  piston  were  the  same,  equal 
movements  of  piston  would  give  equal  power ;  if  therefore  the 
mixtures  gave  equally  good  results  the  maximum  pressure  multiplied 
by  the  piston  area  will  in  all  cases  be  the  same. 

Multiplying  14,  12,  10,  8  and  6  by  their  corresponding  pres- 
sures 52,  63,  69,  89,  and  96  respectively,  the  products  are  728, 
756,  690,  712,  and  576.  These  numbers  are  the  pressures  in 
pounds  which  each  mixture  is  capable  of  producing  with  one 
cubic  inch  of  Glasgow  coal  gas,  cylinders  of  such  area  being  used 
that  the  depth  of  mixture  is  in  every  case  one  inch. 

Proportion  of  Glasgow  gas  in  mixture      ^,    T^,     ^,     1,      A. 

Pressure  produced  upon  pistons  by  )        0       ,    , 

[    728»  756,  690,  712,  576  pounds, 
one  cubic  inch          .         .         .       ) 

The  best  mixture  is  seen  at  a  glance  ;  it  is  that  containing 
one-twelfth  of  gas.  The  pressure  produced  by  one  cubic  inch  of 
gas  is  at  its  highest  value  756  pounds,  in  a  cylinder  of  12  inches 
piston  area,  and  containing  12  cubic  inches  of  mixture. 

In  modern  gas  engines  the  time  taken  by  the  piston  to  make 
the  working  part  of  its  stroke  is  generally  about  one- fifth  of  a 
second.  If  the  pressure  in  one  mixture  has  fallen  more,  proportion- 
ally in  that  time,  then  although  it  may  give  the  highest  maximum, 
it  may  lose  too  rapidly  to  give  the  highest  mean  pressure.  To  find 
this  cooling  effect,  find  the  pressure  to  which  each  mixture  falls 
at  the  end  of  0*2  second  after  maximum  pressure  ;  it  is  in  the 
different  cases  : 

Mixture  containing  gas  .         .    T'T,      T^,      -i,     |r       1. 

Time  after  beginning  explosion  (0*2  )          0         0 

,.  v        [    0'A.S,  0-38,,  o'33,  o'27,,  Q-ZC.  sec. 

sec.  after  max.  pressure)          .        J 

Pressure  in  Ibs.  per  sq.  in  .         .         .43.    48,    47,    55,    57. 

Press,  respectively  by  14,  12,  ID,  8,  )     , 
and6  /  ^        {-602,576,470,440,342. 

The  lower  row  expresses  the  relative  pressures  still  remaining 
after  allowing  each  explosion  to  cool  for  one- fifth  of  a  second 
from  complete  explosion  ;  they  express  the  resistance  to  cooling 
possessed  by  the  mixtures.  It  is  evident  at  once  that  the 


Explosion  in  a  Closed  Vessel  103 

strongest  mixtures  cool  most  rapidly  ;  a  higher  temperature  being 
produced,  more  of  the  heat  of  the  explosion  is  lost  in  a  given  time. 

(2)  Po\ver  of  producing  pressure  and  resisting  cooling. 

To  find  the  best  mixture  for  producing  pressure  and  resisting 
cooling,  those  numbers  are  to  be  added  to  the  corresponding  ones 
for  maximum  pressure  : 

Proportion  of  Glasgow  gas  in  mixture    TJT,    TV,    T\y,    i,     1. 


Pressure  produced  upon  pistons  by  » 
one  cubic  inch  gas          .         .         .  > 


fi       ?12>      ^ 


Pressure  remaining  upon  pistons  o'2  ,     ^       , 

sec.  after  complete  explosion          .  > 
Mean  pressure  .....       665,  666,  580,  576,  459. 

The  mean  of  the  two  sets  gives  numbers  expressing  the 
relative  values  of  the  mixture  for  producing  pressure,  and  at  the 
same  time  resisting  cooling.  The  two  weakest  mixtures  are  best 
in  both  respects,  the  low  result  given  by  the  strongest  mixture  is 
due  to  the  fact  that  excess  of  gas  is  present  and  it  remains  unburned, 
it  proves  how  easily  the  consumption  of  an  engine  may  be  increased 
by  even  a  slight  excess  of  gas  in  the  mixture. 

The  two  best  mixtures  ignite  too  slowly,  but  in  the  actual 
engine  that  is  easily  controlled,  as  will  be  explained  later. 
The  best  mixtures  are  i  vol.  gas  13  volumes  air,  and  i  vol. 
gas  ii  volumes  air.  With  more  gas  the  economy  will  rapidly 
diminish. 

The  experiments  with  Oldham  gas  treated  in  the  same  way 
give  the  following  results  : 

/n  }      TV-    TV.    TV    T\-    iV-    i     i     *•      * 

Pressure  produced  upon  pistons  j  6  6  6> 

by  one  cubic  inch  gas  . 

Pressure  remaining  upon  p:stons  \ 

0-2  sec.  after  complete  explo-  'r     3*.    4o,    4  •    44-    44.    47-    52>    5°.    4& 

sion  per  sq.  inch  ) 

Pressure  per  piston          .         .  .  4^5  560,  546,  528,  44°.  3/6,  364.  3<*>.  23°- 

Mean  pressure  upon  piston     .  .  532,  640,  663,  630,  610,  536,  497,  423,  315. 

Here,  too,  the  best  mixture  lies  between  one-twelfth  and  one- 
fourteenth  of  gas  ;  with  less  and  more  gas  the  result  becomes  worse 
and  worse.  Glasgow  and  Oldham  gases  seem  to  be  very  nearly 
equal  in  value  per  cubic  foot  for  the  production  of  power,  as  the 


IO4  The  Gas  Engine 

pressure  produced  from  one  cubic  inch  in  the  best  mixture  of 
each  is  very  similar.  The  average  pressures  during  0*2  second 
from  complete  explosion  are  exceedingly  close,  Glasgow  gas 
mixture  containing  one-twelfth  gas  giving  666  Ibs.  pressure  per 
cubic  inch  of  gas,  and  Oldham  gas  for  the  same  mixture  and  the 
same  quantity  giving  630  Ibs.:  Glasgow  gas  one-fourteenth  mixture 
665  Ibs.  pressure,  Oldham  gas  640  Ibs.  The  hydrogen  experiments 
give  as  follows  : 

Proportion  of  hydrogen  gas  in  mixture  .  |,      \,      f . 

Pressure  produced  upon  pistons  by  one  ^  ^  2ga 

cubic  inch  hydrogen   .        .         .         .  > 
Pressure   remaining    upon   pistons  o'2\ 

sec.  after  complete  explosion  per  sq.  j-  35,    39,    40. 

inch. .         .         .         .         .         .         .  ) 

Pressure  per  piston        .         .  245,  195,  140. 

Mean  pressure  upon  piston  .         .         .  266,  267,  210. 

The  best  mixture  with  i  cubic  inch  of  hydrogen  only  gives  a 
pressure  of  267  Ibs.  available  for  0*2  second,  so  that  its  capacity 
for  producing  power,  compared  with  Glasgow  and  Oldham  gas,  is 
as  267  is  to  665  and  640  respectively.  To  produce  equal  power 
with  Glasgow  gas  nearly  two-and  a-half  times  its  volume  of  hydrogen 
is  required.  The  idea  is  very  prevalent  among  inventors  that  if 
pure  hydrogen  and  air  could  be  used,  greater  power  and  economy 
would  be  obtained  ;  these  experiments  prove  the  fallacy  of  the 
notion.  Hydrogen  is  the  very  worst  gas  which  could  be  used  in 
the  cylinder  of  a  gas  engine,  it  is  useful  in  conferring  inflamma- 
bility upon  dilute  mixtures  of  other  gases,  but  when  present  in 
large  quantity  in  coal  gas  it  diminishes  its  value  per  cubic  foot  for 
power. 

PRESSURES  PRODUCED  IF  NO  Loss  OR  SUPPRESSION 
OF  HEAT  EXISTED. 

From  the  fact  already  mentioned  in  the  last  chapter,  that  the 
theoretical  temperatures  of  combustion  are  never  attained  in 
reality,  it  will  naturally  be  expected  that  the  pressures  produced 
by  explosions  in  closed  vessels  will  also  fall  short  of  theory. 
This  is  found  to  be  the  case.  It  has  been  observed  by  every 
experimenter  upon  the  subject,  beginning  with  Him  in  1861, 
who  determined  the  pressures  produced  by  the  explosion  of  coal 


Explosion  in  a  Closed  Vessel  105 

gas  and  air,  and  hydrogen  and  air.  He  used  two  explosion  vessels 
of  3  and  36  litres  capacity  ;  they  were  copper  cylinders  with  dia- 
meters equal  to  their  length.  He  used  a  Bourdon  spring  mano- 
meter to  register  the  pressure.  He  states  that  : 

(1)  With  10  per  cent,  hydrogen  introduced  the  results  were  : 
according  to  experiment,  3*25  atmospheres  ;  according  to  calcu- 
lation, 5*8  atmospheres. 

(2)  With  20  per  cent,  of  hydrogen,  the  results  were  :  according 
to  experiment,  7  atmospheres,  which  is  very  much  below  the  cal- 
culation. 

(3)  With   10  per  cent,  of  lighting  gas  introduced  the  results 
were  :  according  to  experiment,  5   atmospheres,  i.e.  much  more 
than  with  the  introduction  of  an  equal  volume  of  pure  hydrogen. 

He  notices  especially  the  low  pressure  produced  by  hydrogen 
as  compared  with  lighting  gases,  but  observes  truly  that  this  should 
not  excite  surprise— although  the  heat  value  of  hydrogen  is  great, 
yet  it  is  so  when  compared  with  equal  weights  of  other  substances—- 
and that  coal  gas  being  four  or  five  times  as  heavy  as  hydrogen, 
quantity  is  balanced  against  quality  ;  therefore  volume  for  volume 
it  gives  out  more  heat. 

He  considers  that  there  is  no  difficulty  in  explaining  the  very 
considerable  difference  found  between  calculation  and  experiment, 
as  the  metal  sides  are  at  so  low  a  temperature  compared  with  the 
explosion,  that  the  heat  i<;  rapidly  conducted  away,  and  the 
attainment  of  the  highest  temperature  is  impossible.  Bunsen,  in 
his  experiments,  observed  the  same  difference,  and  so  later  did 
Mallard  and  Le  Chatelier.  The  author's  experiments  fully 
confirm  the  accuracy  of  those  observers.  In  no  case,  whether 
with  weak  or  strong  mixtures  of  coal  gas  and  air,  or  hydrogen 
and  air,  is  the  pressure  produced  which  should  follow  the  com- 
plete evolution  of  heat. 

Thus,  with  hydrogen  mixtures  (Clerk's  experiments)  : 

Per  sq.  in. 
i  vol.  H  6  vols.  air  gives  by  experiment  .       41  Ibs.  above  atmosphere. 


The  calculated  pressure  is    . 
T  vol.  H  4  vols.  air  experiment  gives  . 

Calculated  pressure  is  . 
2  vols.  H  5  vols.  air  experiment  gives 


88-3 
68 
124 
80 


Calculated  pressure  is .        .        ,        .        .     176 


ic6 


The  Gas  Engine 


Without  exception  the  actual  pressure  falls  far  short  of  the 
calculated  pressure  ;  in  some  manner  the  heat  is  suppressed  or 
lost.  That  the  difference  cannot  altogether  be  accounted  for  by 
loss  of  heat  is  easily  proved ;  the  fall  of  pressure  is  so  slow  from 
the  maximum  that  it  is  impossible  that  any  considerable  proportion 
of  heat  can  be  lost  in  the  short  time  of  explosion.  If  so  large  a 
proportion  were  lost  on  the  rising  curve,  it  could  not  fail  to  show 
upon  the  falling  curve  ;  it  would  fall  in  fact  as  quickly  as  it  rose. 
Again,  the  increase  of  pressure  would  be  less  in  a  small  than  in  a 
large  vessel,  as  the  small  vessel  exposes  the  larger  surface  pro- 
portionally to  the  gas  present.  It  is  found  that  this  is  not  so. 
Bunsen  used  a  vessel  of  a  few  cubic  centimetres  capacity,  and  got 
with  carbonic  oxide  and  oxygen  true  explosive  mixture  io'2  atmo- 
spheres maximum  pressure  ;  Berthelot  with  a  vessel  4000  cb.  c. 
capacity  got  10*1  atmospheres  ;  with  hydrogen  true  explosive 
mixture  Bunsen  9*5  atmospheres,  Berthelot,  9*9  atmospheres.  All 
the  difference,  therefore,  cannot  be  accounted  for  by  loss  before 
complete  explosion. 

Mixtures  of  air  and  coal  gas  give  similar  results. 

The  following  are  the  observed  and  calculated  pressures  for 
Oldham  coal  gas.  (Clerk's  experiments^) 

Per  sq.  in'. 
i  vol.  gas  14  vols.  air,  experiment  gives      .         .       40  Ibs.  above  atmosphere 

Calculated  pressure  is  .         .         .         .  89 '5 
i  vol.  gas  13  vols.  air,  experiment  gives       .         .       51-5 

Calculated  prtssure  is 96 

i  vol.  gas  12  vols.  air,  experiment  gives       .         .       60 

Calculated  pressure  is 103 

i  vol.  gas  ii  vols.  air,  experiment  gives       .         .       61 

Calculated  pressure  is  .         .         .         .         ,112 
i  vol.  gas  9  vols.  air,  experiment  gives         .         .       78 

Calculated  pressure  is 134 

i  vol.  gas  7  vols.  air,  experiment  gives         .         .       87 

Calculated  pressure  is  .         .         .         .         .  168 
i  vol.  gas  6  vols.  air,  experiment  gives         .         .       90 

Calculated  pressure  is  .         .         .         .         .  192 

The  results  with  Glasgow  gas  are  so  similar  that  t  is  unneces- 
sary to  give  a  table  ;  in  ho  case  does  the  maximum  pressure 
account  for  much  more  than  one-half  of  the  total  heat  pre- 
sent. As  all  of  the  deficit  cannot  have  disappeared  previous 
to  complete  explosion,  it  follows  that  the  gases  are  still  burning 
on  trie  falling  curve,  that  is,  the"  falling  curve  does  not  truly 


Explosion  in  a  Closed  Vessel  107 

represent  the  rate  of  cooling  of  air  heated  to  the  maximum  tem- 
perature, because  heat  is  being  continually  added  by  the  continued 
combustion  of  the  mixture.  This  will  be  fully  proved  by  a  study 
of  the  curves. 

It  may,  however,  be  taken  as  completely  proved  by  the 
complete  accord  of  all  physicists  who  have  experimented  on  the 
subject,  that  for  some  reason  nearly  one-half  of  the  heat  present 
as  inflammable  gas  in  any  explosive  mixture,  true  or  dilute,  is 
kept  back  and  prevented  from  causing  the  increase  of  pressure  to 
be  expected  from  it.  Although  differences  of  opinion  exist  on  the 
cause,  all  are  agreed  on  the  fact  ;  they  also  agree  in  considering 
that  inflammation  is  complete  when  the  highest  pressure  is 
attained. 

TEMPERATURES  OF  EXPLOSION. 

With  a  mass  of  any  perfect  gas  confined  in  a  closed  vessel  the 
absolute  temperatures  and  pressures  are  always  proportional ;  double 
temperature  means  double  pressure.  Temperatures  T,  /  (absolute), 

1"*  "p 

pressures  corresponding  P,/;  then  -  =  -  (Charles's  law).       If  ex- 

/       p 

plosive  mixtures  behaved  as  perfect  gases,  the  pressure  before 
explosion  and  temperature  being  known,  the  pressure  of  ex- 
plosion at  once  gives  the  corresponding  temperature.  It  has 
been  shown  at  page  82  that  explosive  mixtures  do  not  fulfil 
this  condition,  but  change  in  volume  from  chemical  causes 
quite  apart  from  physical  ones.  It  follows,  therefore,  that  these 
changes  must  be  known  before  the  temperature  of  the  explosion 
can  be  calculated  from  the  pressure.  In  the  cases  of  hydrogen 
and  carbonic  oxide  true  explosive  mixtures  with  oxygen,  a 
contraction  of  volume  is  the  result  of  combination.  It  comes  to 
the  same  thing  as  if  a  portion  of  the  perfect  gas  in  the  closed 
vessel  was  lost  during  heating  ;  the  temperature  then  could  not 
be  known  at  the  higher  pressure  unless  the  volume  lost  is  also 
known. 

Suppose  one-third  of  the  volume  to  disappear,  upon  cooling 
to  the  original  temperature,  the  pressure  would  be  reduced 'to 
two-thirds  of  the  original  pressure,  and  this  fraction  of  the 
original  pressure  must  be  taken  as  /i  —  io.  As  both  steam  and 


io8  The  Gas  Engine 

carbonic  acid  at  temperatures  high  enough  to  make  them  per- 
fectly gaseous  occupy  two-thirds  of  the  volume  of  their  free 
constituents,  it  follows  that  jf>l  must  be  taken  as  §  /,  wherever 
the  temperatures  are  such  that  combination  is  complete.  But 
here  another  difficulty  occurs.  Bunsen  found  that  hydrogen 
and  oxygen  in  true  explosive  mixtures  gave  an  explosion  pressure 
of  9*5  atmospheres.  The  calculated  pressure  for  complete  combus- 
tion, and  allowing  for  chemical  contraction  is  21  '3  atmospheres.  It 
is  evident  enough  that  complete  combustion  has  not  occurred,  but 
it  is  difficult  to  say  what  fraction  remains  uncombined.  Yet 
unless  the  fraction  in  combination  be  known  the  contraction  cannot 
be  known,  and  therefore  the  temperature  corresponding  to  the 
pressure  cannot  be  known. 

Berthelot  has  pointed  out  that  in  a  case  of  this  kind  the  true 
temperature  cannot  be  calculated,  but  it  may  be  shown  to  lie 
between  two  extreme  assumptions,  both  of  which  are  erroneous. 

(1)  Temperature  calculated  on  assumption  of  no  contraction. 

(2)  Temperature  calculated   on  assumption  of  the  complete 
contraction. 

Let  the  two  temperatures  be  (i)  T1  and  (2)  T. 

T'  T 

2  vols.  H,  i  vol.  O,  explosion  pressure)        2440° C.          3809° C 

(absolute)  9-9  atmospheres          .         .  i 
2  vols.  CO,  i  vol.  O,  explosion  pressure*  6     °  C  °f 

(absolute)  io'8  atmospheres        .         .1 

The  lower  temperature  could  only  be  true  if  no  combination 
whatever  had  occurred,  which  is  impossible,  as  then  no  heat  at  all 
could  be  evolved;  the  higher  temperature  could  only  be  true  if  com- 
plete combination,  and  therefore  complete  contraction,  occurred. 
The  truth  is  somewhere  between  these  numbers. 

When  the  explosive  mixture  is  dilute,  the  limits  of  possible 
error  are  narrower,  because  the  possible  proportion  of  contraction 
is  less  ;  with  hydrogen  and  air  mixture  in  proportion  for  complete 
combination,  2  volumes  of  hydrogen  require  5  volumes  of  air. 
The  greatest  possible  contraction  of  the  7  volumes  is  therefore  i 
volume.  If  all  the  hydrogen  burned  to  steam,  the  7  volumes 
contract  to  6  volumes.  With  more  dilute  mixtures  the  pro- 
portion diminishes. 

WTith   a   mixture  containing  £  of  its   volume    hydrogen,    10 


Explosion  in  a  Closed  Vessel 


109 


volumes  can  only  suffer  contraction  to  9  volumes.    With  \  volume 
hydrogen,  14  volumes  can  contract  to  13  volumes. 

The  limits  of  maximum  temperatures  for  those  mixtures  are  as 
follows  (Clerk)  : 


i  vol.  H,  6  vols.  air,  explosion  pressure  | 
(absolute),  557  Ibs.  per  sq.  in.  .         .  ( 

1  vol.  H,  4  vols.  air,  explosion  pressure  \ 
(absolute),  827  Ibs.  per  sq.  in.  .         .  1" 

2  vols.  H,  5  vols.  air,  explosion  pressure  ^ 
.(absolute),  947  Ibs.  per  sq.  in.  .         .  ) 


Tl 

826°  C. 

1358° c. 

1615°  C. 


T 

909°  C. 

iS39° C. 
1929°  C. 


The  possible  error  is  here  much  less  than  with  true  explosive 
mixtures  ;  coal  gas  is  of  such  a  composition  that  some  of  its 
constituents  expand  upon  decomposition  previous  to  burning,  and 
so  to  some  extent  balance  the  contraction  produced  by  the 
burning  of  the  others.  The  possible  error  is  therefore  still  further 
reduced.  The  composition  of  Manchester  coal  gas  as  determined 
by  Bunsen  and  Roscoe  is  as  below.  The  oxygen  required  for  the 
complete  combustion  of  each  constituent  is  also  given,  and  the 
volumes  of  products  formed. 

ANALYSTS  OF  MANCHESTER  COAL  GAS.     (Bunsen  and  Roscoe.} 


Amount  required 
for  complete 
combustion 

Products 

Hydrogen,  H 
Marsh  gas,  CH4  . 
Carbonic  oxide,  CO 
Ethylene,  C2H4  . 
Tetrylene,  C4H8  . 
Sulphuretted  hydrogen,  H2S 
Nitrogen,  N 
Carbonic  acid,  CO2 

vols. 

45-58 

34  '9  . 
6-64 
4-08 
2-38 

O"29 
2  '46 
S^ 

vols.  O 
,   2279 
69-8 
3'32 

12  '24 
I4-28 
0'43 

vols. 
45-58,  HoO 
104-7,    CO2  &  H2O 
6-64,  CO2 
16-32,  CO2&HoO 
i9-o4)C02&H.;0 
0-58,  H2O&SO2 
2-46 
3-67 

Total    .         .         . 

TOO  '00 

j  22  '86  O 

198-99,  CO2H2O&SO2 

When  burned  in  oxygen  TOO  volumes  of  this  sample  of  gas 
require  122*86  volumes  of  oxygen,  total  mixture  222*86  volumes; 
the  products  of  the  combustion  measure  198 '99  volumes.  Calcula- 
ting to  percentage,  100  volumes  of  the  mixture  will  contract  to  89*4 


no 


The  Gas  Engine 


volumes  of  the  products.  As  100  volumes  of  the  mixture  will 
contain  55*1  volumes  of  oxygen,  it  follows  that  if  air  be  used,  four 
times  that  volume  of  nitrogen  will  be  associated  with  it,  that  is, 
55 -i  x  4  =  220-4.  The  strongest  possible  explosive  mixture  of 
this  coal  gas  with  air  containing  100  volumes  of  the  true  explosive 
mixture  will  be  320-4  volumes,  and  it  will  contract  upon  complete 
combustion  to  309-8  volumes. 

One  volume  of  this  gas  requires  6*14  volumes  air  for  complete 
combustion,  and  TOO  volumes  of  the  mixture  contract  to  96-6 
volumes  of  products  and  diluent.  A  contraction  of  3-4  per  cent. 
Dilution  still  further  diminishes  the  change  ;  thus  a  mixture,  i 
volume  gas  13*28  volumes  air,  will  have  only  half  that  contraction, 
or  1-7  per  cent. 

From  these  figures  it  is  evident  that  the  limits  of  possible 
error  in  calculating  temperature  from  pressure  of  explosion  does 
not  exceed,  in  the  worst  case,  wath  coal  gas  and  air  3-4  per  cent, 
and  in  weaker  mixtures  half  that  number.  The  fact  that  the  whole 
heat  is  not  evolved  at  the  explosion  pressure,  and  that  therefore 
the  whole  contraction  does  not  occur  then,  further  reduces  the 
error.  It  is  then  nearly  correct  to  calculate  temperature  from 
pressure  without  deduction  for  contraction.  This  has  been  done 
for  Glasgow  gas  and  for  the  Oldham  gas  experiments  by  the 
author. 

EXPLOSION  IN  A  CLOSED  VESSEL.     (Clerk.) 

Mixtures  of  air  and  Glasgow  coal  gas. 

Temp,  before  explosion          .         .         .         t         .         .     18°  C. 
Pressure  before  explosion       .         .         .         ...         .     atmos.  147  Ibs. 


Mixture 

Max.  press,  above  atmos. 
in  pounds  per  sq.  in. 

Temp,  of  explosion 
calculated  from 
observed  pressure 

Gas. 

Air. 

vol. 
vol. 
vol. 
vol. 
vol. 

13  vols. 
ir  vols. 
9  vols. 
7  vols. 
5  vols. 

52 
63 
69 
89 
96 

1047°  C. 
1265°  C. 
1384°  C. 
1780°  C. 
1918   C. 

Explosion  in  a  Closed  Vessel 


Mixtures  of  air  and  Oldham  coal  gas. 
Temp,  before  explosion 


17°  C. 


Mixture 

Max.  press,  above 
atmos.  in  pounds 

Temp,  of  explosion 
calculated  from 

Theoretical  temp, 
of  explosion  if  all 

per  sq.  in. 

observed  pressure 

heat  were  evolved 

1 

Gas. 

Air. 

vol. 

14  vols. 

40 

806°  C. 

1786°  C. 

vol. 

13  vols. 

SI'S 

1033°  C. 

i9i2J  C. 

vol. 

12  VolS. 

60 

1202°  C. 

2058   C. 

vol. 

ii  vols. 

61 

1220°  C. 

2228°  C. 

vol. 

9  vols. 

78 

1557°  C. 

2670°  C. 

vol. 

7  vols. 

87 

1733°  C. 

3334'  C. 

vol. 

6  vols. 

90 

1792°  C. 

3808   C. 

vol. 

5  vols. 

91 

!8l2JC. 

vol. 

4  vols. 

80 

1595°  C. 

Those  temperatures  calculated  from  maximum  pressure, 
although  not  quite  true  are  very  nearly  so,  whatever  be  the  theory 
adopted  to  explain  the  great  deficit  of  pressure.  It  'does  not  follow, 
however,  that  they  are  the  highest  temperatures  existing  at  the 
moment  of  explosion  ;  they  are  merely  averages.  The  existence  of 
such  an  intensely  heated  mass  of  gas  in  a  cold  cylinder  causes 
intense  currents,  so  that  the  portion  in  close  contact  with  the 
cold  walls  will  be  colder  than  that  existing  at  the  centre.  There 
will  be  a  hot  nucleus  of  considerably  higher  temperature  than 
that  outside,  but  whatever  that  temperature  may  be,  the  increase 
of  pressure  gives  a  true  average.  It  may  be  taken,  then,  that 
coal  gas  mixtures  with  air  give  upon  explosion  temperatures 
ranging  from  800°  C  to  nearly  2000°  C.,  depending  on  the  dilution 
of  the  mixture.  The  more  dilute  the  mixture  the  lower  the 
maximum  temperature  ;  increase  of  gas  increases  maximum  tempe- 
rature at  the  same  time  as  it  increases  inflammability. 

The  author  has  made  explosion  experiments  in  the  same 
vessel  with  mixtures  previously  compressed,  and  finds  that  the 
pressures  produced  with  any  given  mixture  are  proportional  to 
the  pressure  before  ignition,  that  is,  with  a  mixture  of  constant 
composition,  double  the  pressure  before  explosion,  keeping  tempe- 
rature constant  at  18°  C.,  doubles  the  pressure  of  explosion.  The 
experiments  are  laborious,  and  they  are  not  yet  complete  for  pub- 
lication, but  the  general  principles  already  developed  are  true  for 
compressed  mixtures  also. 


1 1.2,  The  Gas  Engine 

EFFICIENCY  OF  GAS  IN  EXPLOSIVE  MIXTURES. 

Rankine  defines  available  heat  as  follows  : 

*  The  available  heat  of  combustion  of  one  pound  of  a  given 
sort  of  fuel  is  that  part  of  the  total  heat  of  combustion  which  is 
communicated  to  the  body  to  heat  which  the  fuel  is  burned  ; 
and  the  efficiency  of  a  given  furnace,  for  a  given  sort  of  fuel,  is  the 
proportion  which  the  available  heat  bears  to  the  total  heat.' 

The  gas  engine  contains  furnace  and  motor  cylinder  in  one  ; 
nevertheless  the  efficiency  of  the  working  fluid  is  quite  as  distinct 
from  the  furnace  efficiency  as  in  the  steam  engine.  Rankine's  de- 
finition is  quite  true  for  the  gas  engine. 

The  fuel  being  gas,  the  working  fluid  consists  of  air  and  its  fuel 
and  their  combinations  ;  the  available  heat  is  that  part  of  the 
heat  of  combustion  which  serves  to  raise  the  temperature  of  the 
working  fluid  ;  the  part  which  flows  into  it  to  make  up  for  loss  to 
the  cold  cylinder  walls  cannot  be  considered  available.  To  be 
truly  available  it  must  either  increase  temperature,  or  keep  it 
from  falling  by  expansion.  The  heat  flowing  through  the 
cylinder  walls  is  a  furnace  loss,  incident  to  the  explosion  method 
of  heating. 

The  experiments  upon  explosion  in  a  closed  vessel  provide 
data  for  determining  the  furnace  efficiency  as  distinguished  from 
that  of  the  working  fluid.  The  proportion  of  heat  flowing  from 
an  explosion  to  the  walls  in  unit  time  will  depend  upon  the 
surface  of  the  walls  for  any  given  volume.  The  smaller  the 
cooling  surface  in  proportion  to  volume  of  heated  gases,  the 
slower  will  be  the  rate  of  cooling.  Therefore  to  be  applicable  to 
any  engine,  the  explosion  vessel  in  which  the  experiments  are 
made  should  have  the  same  capacity  and  surface  as  the  explosion 
space  of  the  engine. 

The  author's  experiments  are  therefore  only  strictly  applicable 
to  engines  with  cylinders  similar  to  his  explosion  vessel.  Within 
certain  limits,  however,  the  error  introduced  by  applying  them  to 
other  engines  is  inconsiderable. 

Assuming  the  stroke  of  a  gas  engine  (after  explosion)  to  take 
0-2  second,  this  may  be  taken  as  the  time  during  which  the 
pressure  of  explosion  must  last  if  it  is  to  be  utilised  by  the 


Explosion  in  a  Closed  Vessel  \  \  3 

engine.  In  a  closed  vessel  the  pressure  falls  considerably  in  0-2 
second,  the  average  pressure  may  be  taken  as  nearly  indicating 
the  available  pressure  during  that  time.  The  heat  necessary  to 
produce  that  pressure  is  the  available  heat  ;  and  its  proportion  to 
the  total  heat  which  the  gas  present  in  the  mixture  can  evolve  is 
the  efficiency  of  the  gas  in  that  explosive  mixture. 

With  Oldhamgas  the  best  mixture  is  (table,  p.  103)  i  volume 
gas  1 2  volumes  air  ;  the  average  pressure  during  the  first  fifth  of 
a  second  is  51  Ibs.  per  square  inch  above  atmosphere.  If  all 
the  heat  present  heated  the  air,  the  pressure  should  be  103  Ibs. 
effective,  so  that  the  efficiency  of  the  heating  method  is  -f^  = 
0-49. 

The  strongest  mixture  which  still  contains  oxygen  in  excess 
is  i  volume  gas  7  volumes  air,  the  average  available  pressure  is 
67  Ibs.  per  square  inch  (all  heat  evolved  would  give  168  Ibs.),  the 
efficiency  is  T6&7¥  =  0*40  nearly. 

Calculated  in  this  way  the  efficiency  values  for  Oldham  gas 
mixtures  are  : 

Prop,  of  Oldham  gas  in  mixture  .       •£%,     TaT,      TV,      TV     T\>'      !>       y- 
Heating  efficiency        .         .         .     0^40,  o'48,  O'SQ,  o'43,  o'46,  o^o,  o'37- 

The  furnace  efficiency  plainly  diminishes  with  increased 
richness  of  the  mixture  in  gas. 

TIME  OF  EXPLOSION  IN  CLOSED  VESSELS. 

The  rates  of  the  propagation  of  flame  in  explosive  mixtures 
given  in  tables,  pages  86  and  87,  are  true  only  where  the 
inflamed  portion  is  free  to  expand  without  projecting  itself  into 
the  unignited  portion.  They  are  the  rates  proper  for  constant 
pressure. 

Where  the  volume  is  constant,  in  a  closed  vessel,  the  part  first 
inflamed  instantly  expands  and  so  projects  the  flame  surface  into 
the  mass,  compressing  what  remains  into  smaller  space. 

To  the  rate  of  inflammation  at  constant  pressure  are  added 
the  projection  of  the  flame  into  the  mass  by  its  expansion 
and  also  the  increased  rate  of  propagation  in  the  unignitel 
portion  by  the  heating  due  to  its  compression  by  portion  first 
inflamed. 

i 


1 1.4  The  Gas  Engine 

It  follows  that  the  rate  continually  increases,  as  the  inflamma-* 
tion  proceeds  until  it  fills  the  vessel. 

This  is  evident  from  all  the  explosion  curves.  The  pressure 
rises  slowly  at  first,  then  with  ever  increasing  rate  till  the  explosion 
is  complete  ;  thus  the  explosion  curve  for  hydrogen  mixture  with 

air     (  -   H  J,  shows  an  increase  of  17  pounds  in  the  first  0*005 

second,  the  maximum  pressure  of  80  pounds  being  attained  in  the 
next  o-oo5  second.  With  the  weaker  mixtures  the  same  thing 
occurs,  rise  of  pressure,  slow  at  first,  then  more  rapid,  and  in 
some  cases  becoming  slow  again  before  maximum  pressure.  The 
time  taken  to  get  maximum  pressure  varies  much  with  the  circum- 
stances attending  the  beginning  of  the  ignition.  If  a  considerable 
mass  be  ignited  at  once,  by  a  long  and  powerful  spark,  or  by  a 
large  flame,  the  ignition  of  the  weakest  mixture  may  be  made 
almost  indefinitely  rapid.  Something  very  like  Berthelot's  explo- 
sive wave  may  result.  This  is  due  to  the  great  mechanical 
disturbance  caused  by  the  rapid  expansion  of  the  portion  first 
ignited  ;  the  smaller  that  portion  is  the  more  gently  does  the 
flame  spread.  A  small  separate  chamber  connected  with  the 
main  vessel,  if  filled  with  explosive  mixture  and  ignited,  will 
project  a  rush  of  flame  into  the  main  vessel  and  cause  almost 
instantaneous  ignition.  The  shape  of  the  vessel,  too,  has  a  great 
effect  upon  the  rate.  Where  it  is  cylindrical  and  large  in  diameter 
proportional  to  its  axial  length,  ignition  is  extremely  rapid,  the 
flame  is  confined  at  starting,  and  is  rapidly  deflected  by  the 
cylinder  ends,  and  so  shoots  through  the  whole  mass. 

By  so  arranging  the  explosion  space  of  a  gas  engine  that  some 
mechanical  disturbance  is  permitted,  it  is  easy  to  get  any  required 
rate  of  ignition  even  with  the  .weakest  mixtures. 

The  maximum  pressure  is  not  increased  by  rapid  ignition. 

Starting  the  ignition  from  a  small  spark,  the  time  taken  to 
ignite  increases  with  the  volume  of  the  vessel. 

Berthelot  has  experimented  upon  this  point  with  explosion 
vessels  of  three  capacities,  300  cubic  centimetres,  1500  cubic 
centimetres,  and  4000  cubic  centimetres.  He  finds  time  of 
explosion  (he  also  takes  maximum  pressure  to  indicate  complete 


Explosion  in  a  Closed  Vessel  115 

explosion)  of  mixture  2  vols.  H,  i  vol.  O,  and  2  vols.  N,  in  300 
cubic  centimetre  vessel,  0-0026  second;  and  in  4000  cubic 
centimetre  vessel,  0-0068  second. 

With  mixture  of  carbonic  oxide  and  oxygen,  2  vols.  CO,  i  vol. 
O,  smaller  vessel,  0-0128  second;  larger  vessel,  0*0155  second. 
Mixtures  with  air  were  much  slower.  The  conclusion  then  is 
obvious,  that  in  large  engines  the  time  of  explosion  will  be  longer 
than  in  small  ones. 


The  Gas  Engine 


CHAPTER   VII. 

THE   GAS    ENGINES    OF   THE   DIFFERENT    TYPES    IN    PRACTICE. 

HAVING  now  studied  the  theoretic  efficiency  of  the  different 
kinds  of  engine  and  the  mechanism  of  the  heating  method— that 
is  the  properties  of  gaseous  explosions — the  way  is  clear  for 
the  study  of  the  results  obtained  from  the  engines  in  practice. 

It  is  quite  evident  that  no  practicable  engine  can  give  an 
efficiency  at  all  approaching  theory  from  the  use  of  gaseous 
explosions ;  the  temperatures  and  therefore  pressures  produced 
fall  far  short  of  that  due  to  the  complete  evolution  of  the  heat 
present  in  the  mixture  as  combustible  gas.  All  the  heat  of 
the  gas  does  not  go  to  increase  the  temperature  of  the  working 
fluid  ;  a  large  proportion  of  it  is  rendered  latent  in  some  way 
when  the  maximum  temperature  is  attained. 

The  appearance  of  the  diagrams  from  the  explosion  of  mixtures 
commonly  used  in  gas  engines,  shows  at  first  a  very  rapid  increase 
of  pressure  and  temperature,  which  terminates  abruptly  and  is 
immediately  succeeded  by  a  fall  which  is  relatively  a  slow  one. 

It  was  formerly  supposed  that  the  completion  of  the  explosion 
was  coincident  with  the  completion  of  the  combustion,  and  there- 
fore of  the  evolution  of  heat.  This,  however,  was  shown  by 
Bunsen  and  those  who  have  followed  him,  to  be  untrue  ;  although 
the  temperature  ceases  to  rise,  and  fall  sets  in,  the  gas  present 
has  in  few  explosions  been  more  than  half-burned  at  the  moment 
of  maximum  temperature.  The  causes  which  suppress  the  heat  of 
the  explosion  and  prevent  it  from  being  evolved  at  once  are  com- 
plex and  have  occasioned  different  explanations  which  will  be  fully 
discussed  in  a  subsequent  chapter.  Meantime,  it  is  sufficient 
to  recognise  the  fact  and  to  understand  its  bearing  upon  the 
economy  of  gas  engines. 


Gas  Engines  of  Different  Types  in  Practice         117 

It  is  a  phenomenon  common  to  all  gas  engines  which  have 
ever  been  constructed,  whether  using  compression  previous  to  ig- 
nition or  not.  The  heat  so  suppressed  appears  when  cooling  sets  in, 
and  consequently  explosive  mixtures  cool  more  slowly  in  appear- 
ance than  would  a  mass  of  air  heated  to  similar  temperatures  and 
exposed  to  similarly  cold  enclosing  walls. 

In  many  gas  engines  the  indicator  diagrams  are  apparently 
almost  perfect,  that  is,  the  lines  of  falling  temperatures  are 
almost  true  adiabatics.  So  far  as  the  diagram  yields  informa- 
tion, the  gases  in  expanding  are  losing  no  heat  whatever  to  the 
cylinder,  but  the  temperature  is  falling  apparently  only  by  work  done 
upon  the  piston.  This  supposition  is  known  to  be  untrue,  because 
the  gases  are  at  a  temperature  often  as  high  as  the  hottest  of 
blast  furnaces,  and  the  walls  enclosing  are  at  most  at  the  boiling 
point  of  water.  It  is  the  suppressed  heat  which  is  being  evolved 
during  fall  of  temperature  which  sustains  the  temperature  and 
makes  the  diagram  appear  as  if  no  loss  or  but  little  was  going  on. 
An  actual  engine  therefore  may  give  a  diagram  which  is  the  exact 
theoretical  one,  and  yet  the  efficiency  of  the  engine  be  much 
below  theory.  The  author's  experiments  upon  explosive  mixtures 
were  undertaken  to  get  the  data  necessary  for  the  interpretation  of 
the  diagram,  and  the  rising  and  falling  curves,  showing  times  of 
rise  and  fall  of  pressure,  give  the  efficiency  of  coal  gas  in  the 
different  mixtures,  apart  altogether  from  theoretic  considerations. 
Whatever  the  opinions  held  regarding  the  cause  or  causes  of  the 
suppression  of  heat,  the  experiments  with  carefully  proportioned 
explosive  mixtures,  at  known  temperatures  and  pressures,  deter- 
mine absolutely  the  capability  of  gas  for  producing  pressure  and 
for  sustaining  it  under  cooling. 

As  the  efficiency  may  be  very  different  from  that  shown  by 
the  indicator,  it  is  advisable  to  distinguish  between  the  real  and 
apparent  efficiency.  Call  the  one  apparent  indicated  efficiency, 
and  the  other  actual  indicated  efficiency. 

The  apparent  indicated  efficiency,  when  multiplied  by  the  effi- 
ciency of  the  gas  in  the  particular  mixture  used,  will  give  the  actual 
indicated  efficiency.  For  instance,  if  the  diagram  gave  the  efficiency 
cf  an  engine  as  0*29  and  the  efficiency  of  the  mixture  was  0-48,  then 
the  actual  indicated  efficiency  is  0*29  x  0-48=0-11.  That  is,  only 


! ,  s  The  Gas  Engine 

0-48  of  the  gas  present  when  the  diagram  is  taken  really  acts 
in  producing  elevation  of  temperature;  the  remaining  0-52  is  sup- 
pressed and  keeps  up  the  temperature,  which  would  otherwise  fall 
by  cooling.  The  diagram  alone  can  never  tell  accurately  the 
losses  which  are  taking  place  unless  the  heat  is  all  evolved  at  once 
and  appears  in  temperature;  then,  but  not  till  then,  will  the  lines 
traced  by  the  indicator  tell  the  loss  of  heat.  Some  previous 
writers  have  misinterpreted  their  indicator  diagrams  through 
neglect  of  this  fact. 

Some  others,  notably  Dr.  Slaby,  of  Berlin,  have  assumed  that 
the  phenomenon  of  retarded  combustion  is  produced  by  invention 
and  occurs  only  in  the  Otto  engine.  This  is  a  mistake.  All  engines 
using  explosion  necessarily  exhibit  it  ;  in  fact,  as  it  is  an  accom- 
paniment of  all  explosions,  it  is  impossible  to  make  an  engine  in 
which  it  is  avoided. 

In  the  following  examination  of  the  performances  of  the 
various  engines  in  practice  the  importance  of  the  phenomenon  will 
appear. 

Type  i. — The  most  important  engines  of  this  type  which  have 
yet  been  in  public  use  are  those  of  Lenoir,  Hugon,  and  Bisschoff. 
Many  others  have  been  made  and  sold  in  some  numbers,  but  as 
these  three  present  fully  all  the  peculiarities  of  the  type,  it  would 
only  waste  time  to  describe  the  varied  mechanical  details  consti- 
tuting the  sole  novel  points  in  the  others. 

LENOIR  ENGINE. 

The  Lenoir  engine  as  made  differs  considerably  from  that 
described  in  his  specifications.  As  a  rule  of  almost  general  appli- 
cation, specifications  are  untrustworthy  as  accurate  descriptions  of 
working  machines  ;  the  author  has  been  careful  to  describe  no 
engine  which  he  has  not  examined. 

Fig.  22  is  a  section  of  the  cylinder  of  a  half-horse  power 
Lenoir  engine.  The  engine  in  the  Patent  Office  Museum,  South 
Kensington,  is  well  made  and  in  external  appearance  closely  re- 
sembles an  ordinary  high-pressure  steam  engine. 

The  cylinder  is  5^  inches  diameter,  and  the  stroke  is  Scinches. 
Its  cylinder  is  provided  with  two  valves.;  both  are  slides,  working 


Gas  Engines  of  Different  Types  in  Practice         119 

between  the  cylinder  faces  and  covers,  which  are  held  down  to  the 
slides  by  adjusting  screws.  One  valve  controls  the  discharge 
of  the  products  of  combustion,  the  other,  the  admission  and 
mixing  of  the  inflammable  gas  and  air.  The  ignition  is  effected 
by  the  electric  spark.  The  working  cycle  of  the  engine  io  as 
follows  : 

When  the  piston  is  at  the  end  of  its  stroke,  the  gas  and  air  ad- 
mission valve  is  open  ;  the  main  port  in  it  opens  to  the  atmosphere, 


MIXING 
PLATE  ^ 

TT TT 

FIG.  22.— Lenoir  Engine  Cylinder  (sectional  plan). 

while  a  smaller  port  leads  from  the  main  port  to  the  gas  supply. 
The  forward  movement  of  the  piston  draws  into  the  cylinder  the 
air  and  the  gas,  which  mix  as  they  enter  the  main  valve  port  and  the 
engine  admission  port.  At  about  half-stroke  the  supply  of  mixed 
gases  is  cut  off,  so  that  the  cylinder  is  completely  closed  off  from 
the  atmosphere  and  from  the  gas  supply  ;  an  electric  spark  now 
passed  into  the  explosive  mixture  from  a  battery  and  induction  coils 
explosion  and  the  pressure  rapidly  rises.  The  piston  is 


123  The  Gas  Engine 

thereby  pushed  on  its  stroke  during  the  portion  remaining  to 
be  completed  ;  at  the  end  of  the  stroke  the  pressure  has  fallen 
by  expansion  doing  work  and  by  the  cooling  action  of  the  cylinder 
walls,  to  nearly  atmosphere  again  ;  the  exhaust  valve  opens  and 
during  the  return  stroke  the  products  of  combustion  are  expelled 
preparatory  to  taking  in  a  fresh  charge  upon  the  next  working  stroke. 
The  same  operation  is  repeated  upon  the  other  side  of  the  piston 
so  that  the  engine  is  double-acting  of  a  kind.  It  cannot  be  con- 
sidered as  truly  double-acting,  like  the  steam  engine,  as  the  driving 
pressure  is  not  acting  during  the  whole  forward  stroke,  but  only 
during  that  portion  of  it  which  is  not  taken  up  in  sucking  in 
the  explosive  charge.  The  fly  wheel,  because  of  this,  is  much 
larger  than  in  a  steam  engine  of  corresponding  dimensions, 
and  the  power  is  also  much  less.  The  valves  are  both  actuated  by 
eccentrics  upon  the  crank  shaft.  Each  slide  requires  a  separate 
eccentric  because  the  exhaust  during  the  whole  stroke  and  the 
admission  during  only  half-stroke  could  not  be  managed  by  the 
single  to  and  fro  movement.  To  get  the  best  result  it  is  evident 
that  the  least  possible  power  should  be  expended  in  introducing 
the  charge  ;  therefore,  large  inlet  air  ports  are  required,  all  the 
larger  because  an  eccentric  cannot  be  made,  alone,  to  give  a 
sudden  cut-off.  To  prevent  throttling  as  the  ports  approach 
the  closing  points,  the  total  opening  must  be  considerable.  The 
eccentric  is  so  set  that  the  port  is  open  slightly  before  the  crank 
has  crossed  the  centre,  so  that  it  may  be  well  open  when  the 
charge  begins  to  enter,  In  fact  it  has  some  lead  like  a  steam 
slide,  and  for  the  same  purpose.  The  exhaust  valve  is  set 
precisely  as  in  the  steam  engine,  and  is  of  similar  construction, 
except  that  it  is  not  enclosed  in  a  case,  but  it  is  held  against  the 
cylinder  face  by  a  cover  and  screws.  Fig.  22  is  a  sectional  plan 
of  the  cylinder,  showing  the  valves  and  ports  ;  fig.  23  is  a  trans- 
verse vertical  section  of  the  cylinder,  showing  the  valves  and  valve 
covers  with  gas,  air  and  exhaust  ports.  The  arrows  indicate  the 
direction  of  the  gas  and  air  flow,  while  mixing  and  entering  the 
cylinder,  also  the  exhaust  path.  As  the  air  port  opens  to  the 
cylinder  slightly  before  the  piston  has  completed  its  stroke,  and 
a  slight  pressure  may  yet  remain  in  the  cylinder,  the  gas  port 
does  net  open  till  a  little  later.  The  gas  and  air  do  not  open 


Gas  Engines  of  Different  Types  in  Practice         121 

quite  simultaneously,  although  nearly  so  ;  neither  do  they  close 
quite  together.  There  is  one  gas  admission  port  in  the  slide 
leading  into  the  main  port ;  in  the  cover  there  are  two  ports 
between  which  the  slide  port  passes,  taking  gas  from  either,  as 
is  required,  for  the  end  of  the  cylinder  which  is  receiving  the 
charge.  The  main  valve  port  opens  on  the  upper  side  to  the  air, 
and  is  covered  by  a  perforated  plate  -and  a  light  metal  case 
furnished  with  a  throttle  valve  ;  the  brass  plate  perforated  is 
carried  downwards  and  covers  the  gas  port,  so  that  the  gas 
entering  from  the  supply  pipe  is  not  permitted  to  flow  at  once  into 


Exhaust 


Gas  Inlet 
FIG.  23.  —  Lenoir  Engine  Cylinder  (transverse  section). 

the  main  port,  but  must  first  pass  up  through  the  perforations  and 
mix  with  the  air  which  is  going  down  through  those  adjoining. 
The  mixing  arrangement  is  somewhat  imperfect,  and  is  exceed- 
ingly sensitive  to  change  of  speed  in  the  engine.  The  throttle-valve 
is  intended  to  increase  or  diminish  the  supply  of  air  ;  by  closing 
it  slightly,  the  suction  upon  the  gas  port  is  increased,  and  so 
the  proportion  of  the  mixture  altered.  By  opening  it,  the  air  has 
freer  access  to  the  cylinder,  the  pressure  is  not  reduced  so  much, 
and  therefore  the  gas  is  diminished.  The  mixing,  however,  is  too 
irregular  ;  as  the  gas  streams  are  not  projected  separately  into  the 


I2O  The  Gas  Engine 

thereby  pushed  on  its  stroke  during  the  portion  remaining  to 
be  completed  ;  at  the  end  of  the  stroke  the  pressure  has  fallen 
by  expansion  doing  work  and  by  the  cooling  action  of  the  cylinder 
walls,  to  nearly  atmosphere  again  ;  the  exhaust  valve  opens  and 
during  the  return  stroke  the  products  of  combustion  are  expelled 
preparatory  to  taking  m  a  fresh  charge  upon  the  next  working  stroke. 
The  same  operation  is  repeated  upon  the  other  side  of  the  piston 
so  that  the  engine  is  double-acting  of  a  kind.  It  cannot  be  con- 
sidered as  truly  double-acting,  like  the  steam  engine,  as  the  driving 
pressure  is  not  acting  during  the  whole  forward  stroke,  but  only 
during  that  portion  of  it  which  is  not  taken  up  in  sucking  in 
the  explosive  charge.  The  fly  wheel,  because  of  this,  is  much 
larger  than  in  a  steam  engine  of  corresponding  dimensions, 
and  the  power  is  also  much  less.  The  valves  are  both  actuated  by 
eccentrics  upon  the  crank  shaft.  Each  slide  requires  a  separate 
eccentric  because  the  exhaust  during  the  whole  stroke  and  the 
admission  during  only  half-stroke  could  not  be  managed  by  the 
single  to  and  fro  movement.  To  get  the  best  result  it  is  evident 
that  the  least  possible  power  should  be  expended  in  introducing 
the  charge  ;  therefore,  large  inlet  air  ports  are  required,  all  the 
larger  because  an  eccentric  cannot  be  made,  alone,  to  give  a 
sudden  cut-off.  To  prevent  throttling  as  the  ports  approach 
the  closing  points,  the  total  opening  must  be  considerable.  The 
eccentric  is  so  set  that  the  port  is  open  slightly  before  the  crank 
has  crossed  the  centre,  so  that  it  may  be  well  open  when  the 
charge  begins  to  enter.  In  fact  it  has  some  lead  like  a  steam 
slide,  and  for  the  same  purpose.  The  exhaust  valve  is  set 
precisely  as  in  the  steam  engine,  and  is  of  similar  construction, 
except  that  it  is  not  enclosed  in  a  case,  but  it  is  held  against  the 
cylinder  face  by  a  cover  and  screws.  Fig.  22  is  a  sectional  plan 
of  the  cylinder,  showing  the  valves  and  ports  ;  fig.  23  is  a  trans- 
verse vertical  section  of  the  cylinder,  showing  the  valves  and  valve 
covers  with  gas,  air  and  exhaust  ports.  The  arrows  indicate  the 
d.'rection  of  the  gas  and  air  flow,  while  mixing  and  entering  the 
cylinder,  also  the  exhaust  path.  As  the  air  port  opens  to  the 
cylinder  slightly  before  the  piston  has  completed  its  stroke,  and 
a  slight  pressure  may  yet  remain  in  the  cylinder,  the  gas  port 
does  net  open  till  a  little  later.  The  gas  and  air  do  not  open 


Gas  Engines  of  Different  Types  in  Practice         121 


quite  simultaneously,  although  nearly  so  ;  neither  do  they  close 
quite  together.  There  is  one  gas  admission  port  in  the  slide 
leading  into  the  main  port ;  in  the  cover  there  are  two  ports 
between  which  the  slide  port  passes,  taking  gas  from  either,  as 
is  required,  for  the  end  of  the  cylinder  which  is  receiving  the 
charge.  The  main  valve  port  opens  on  the  upper  side  to  the  air, 
and  is  covered  by  a  perforated  plate  -and  a  light  metal  case 
furnished  with  a  throttle  valve  ;  the  brass  plate  perforated  is 
carried  downwards  and  covers  the  gas  port,  so  that  the  gas 
entering  from  the  supply  pipe  is  not  permitted  to  flow  at  once  into 


Gas  and 
Air  mix  at 
this  point 


Gas  Inlet 
FIG.  23.  —  Lenoir  Engine  Cylinder  (transverse  section). 

the  main  port,  but  must  first  pass  up  through  the  perforations  and 
mix  with  the  air  which  is  going  down  through  those  adjoining. 
The  mixing  arrangement  is  somewhat  imperfect,  and  is  exceed- 
ingly sensitive  to  change  of  speed  in  the  engine.  The  throttle- valve 
is  intended  to  increase  or  diminish  the  supply  of  air  ;  by  closing 
it  slightly,  the  suction  upon  the  gas  port  is  increased,  and  so 
the  proportion  of  the  mixture  altered.  By  opening  it,  the  air  has 
freer  access  to  the  cylinder,  the  pressure  is  not  reduced  so  much, 
and  therefore  the  gas  is  diminished.  The  mixing,  however,  is  too 
irregular  ;  as  the  gas  streams  are  not  projected  separately  into  the 


122  The  Gas  Engine 

incoming  air  stream,  the  gas  flows  too  much  in  mass  into  the  air 
in  mass.  The  igniting  points  were  invariably  placed  at  the  upper 
part  of  the  cylinder  in  the  cylinder  covers.  The  cylinder  and  covers 
are  waterjacketed,  the  water  is  kept  continuously  flowing  through, 
so  that  the  temperature  may  not  become  so  high  as  to  injure  the 
cylinder.  This  is  a  most  necessary  precaution  in  any  gas  engine 
of  even  moderate  power  ;  the  effect  of  neglect  in  a  Lenoir  engine 
is  very  soon  observed  in  complete  cutting  up  of  the  cylinder  ;  it 
speedily  becomes  red-hot  if  allowed  to  run  without  water,  In- 
deed, even  with  an  adequate  water  supply,  the  larger  engines  gave 
great  trouble  ;  although  the  cylinder  could  be  kept  cool  the  piston 
could  not.  It  was  proportioned  too  much  on  steam  engine  lines, 
and  when  working  at  full  power  the  incessant  explosions  upon  both 
sides  caused  so  rapid  a  flow  of  heat  into  it  that  the  small  surface 
exposed  to  the  water  jacket  by  the  circumference  was  insufficient 
to  carry  away  the  heat  absorbed  by  the  whole  piston  area.  The 
pistons  often  became  red-hot. 

The  exhaust  slide  also  had  rather  hard  work,  and  required 
delicate  adjustment,  as  the  exhaust  gases  were  very  hot,  often 
800°  C ;  the  expansion  of  the  slide  was  therefore  considerable, 
and  in  order  to  be  pressure  tight  when  hot,  the  adjusting  screws 
had  to  be  kept  rather  easy  when  cold.  The  engine  when 
starting,  therefore,  always  leaked  a  little  at  the  exhaust  valve. 
The  same  thing  happened  with  the  admission  slide,  but  to  a  lesser 
degree. 

Notwithstanding  the  large  area  of  the  admission  port  and  the 
lead  given  to  the  admission  valve,  the  closing  motion  was  too 
slow  to  prevent  throttling  ;  accordingly  the  pressure  fell  some- 
what below  atmosphere,  while  the  valve  was  cutting  off  preparatory 
to  explosion.  After  cutting  off  a  slight  delay  occurred  between  the 
passing  of  the  spark  and  the  commencement  of  the  explosion  ; 
the  explosion  itself  took  some  time  to  complete  ;  it  was  by  no 
means  instantaneous  ;  the  diagram  produced  was  consequently 
imperfect.  In  addition  to  all  this,  the  piston  ,being  so  hot,  heated 
the  charge  while  it  was  entering,  and  so  occasioned  further 
loss. 

The  lubricating  arrangements  also  were  primitive.  The 
steam  engine  requiring  but  little  care  in  lubricating,  the  gas 


Gas  Engines  of  Different  Types  in  Practice         ,123 

engine  was  not  supposed  to  require  more ;  and  the  ordinary  lubri- 
cating cock  was  deemed  sufficient.  All  these  sources  of  loss, 
inevitable  in  a  first  attempt,  made  the  engine  comparatively  in- 
efficient Notwithstanding  all  its  defects,  the  Lenoir  engine  at  the 
time  of  its  production  was  the  best  the  world  had  yet  seen,  and  in 
careful  hands  it  did  good  work  and  created  a  widespread  interest. 
The  engine  in  South  Kensington  Museum,  under  the  skilful  care  of 
Mr.  S.  Ford,  worked  for  many  years  supplying  all  the  power  required 
for  the  repair  department  of  the  Patent  Office  Museum.  It  runs  with 
perfect  smoothness,  nothing  whatever  in  its  action  would  enable 
one  standing  beside  it  to  imagine  for  a  moment  that  the  motive 
power  was  explosive.  The  popular  notion  of  an  explosion  is  always 
associated  with  the  idea  of  a  great  noise.  This,  of  course,  physicists 
have  always  known  to  be  a  fallacy,  as  no  explosion  makes  noise 
unless  it  has  access  to  the  atmosphere.  An  explosion  in  a  closed 
vessel  makes  no  sound  unless  the  vessel  bursts.  In  a  gas  engine 
it  is  only  necessary  to  see  that  the  explosion  is  not  too  rapid,  but 
that  time  is  allowed  for  the  slack  of  the  connecting  rod  and  crank 
connections  to  take  up.  The  explosions  used  by  Lenoir  were 
seldom  more  rapid  in  rise  of  pressure  than  is  common  with  all 
steam  engines.  A  i -horse  Lenoir  engine  inspected  lately  by  the 
author  at  Petworth  House,  Petworth,  had  been  at  work  for  the 
past  twenty  years  pumping  water  for  the  town  and  is  still  at  work. 
It  works  with  smoothness  and  is  altogether  more  silent  in  its  action 
than  most  modern  gas  engines.  The  author  finds  that  many  Lenoir 
engines  are  still  at  work  after  twenty  years'  continuous  use,  notably 
two  i -horse  power  engines  at  the  Brewery  of  Messrs.  Trueman, 
Hanbury  and  Buxton,  London,  arid  one  i -horse  power  at  the 
establishment  of  Messrs.  Day,  Son  and  Hewitt,  Dorset  Street, 
London,  all  doing  hard  work  with  great  regularity. 

Diagrams  and  Gas  consumption. — Prof.  Tresca  of  Paris  has  made 
experiments  with  a  ^-horse  Lenoir  engine,  and  found  that  it  con- 
sumed 95  cb.  ft.  of  Paris  gasper  indicated  horse  power  per  hour.  The 
diagrams  from  so  small  an  engine  hardly  do  justice  to  the  method, 
and  as  it  is  desirable  to  compare  the  engine  with  modern  engines 
using  similar  volumes  of  charge  the  author  has  taken  a  diagram  from 
a  paper  by  Mr.  Slade,  published  in  the  Journal  of  the  Franklin 
Institute,  Philadelphia.  The  engine  had  a  cylinder  of  eight  inches 


124 


The  Gas  Engine 


diameter  and  sixteen  stroke.  The  explosion  space  corresponds 
closely  to  that  of  the  author's  experimental  explosion  vessel. 

The  diagram,  fig.  24,  at  once  shows  the  truth  of  the  preceding 
discussion  of  the  action  of  the  engine. 

AB  is  the  atmospheric  line,  traced  upon  the  indicator  card 
by  the  pencil  before  opening  the  indicator  cock  to  communicate 
with  the  interior  of  the  cylinder  ;  it  is  the  neutral  position  of  the 
indicator  piston  while  the  pressure  on  both  sides  of  it  is  at  atmo- 
sphere ;  any  pressure  from  within  the  cylinder  pushes  up  the  piston 
and  therefore  the  indicator  pencil.  Pressure  above  atmosphere 
is  registered  by  lines  above  that  line,  pressure  below  atmosphere 


Diagram  at  50  revolutions,  cylinder  85  inches  diameter,  16}  inches  s'roke. 
FIG.  24.  — Lenoir  Engine  Diagram. 

is  registered  by  lines  below  that  line.  The  card  shows  three  dis- 
tinct tracings,  each  corresponding  to  one  stroke  of  the  engine  : 
admission  of  the  charge,  explosion,  expansion  and  return  expel- 
ling the  products  of  the  combustion.  If  the  cycle  is  carried 
out  in  a  mechanically  perfect  manner  the  admission  of  the  charge 
should  be  accomplished  without  loss  by  throttling.  This  is  not  so. 
From  the  point  a  to  the  point  b  the  valve  is  open  enough  to  give 
free  access  to  the  cylinder,  and  accordingly  the  pressure  within  the 
cylinder  is  not  appreciably  lower  than  that  without  ;  but  here  the 
valve  begins  to  contract  its  opening  at  the  very  moment  that 
the  piston  is  moving  most  rapidly,  the  pressure  falls  and  is  a  couple 
of  pounds  per  square  inch  below  atmosphere  when  it  closes. 
When  closed,  the  spark  does  not  at  once  take  effect,  so  that  the 
pressure  has  become  1 1  Ibs.  per  sq.  in.  total  before  the  igni- 


Gas  Engines  of  Different  Types  in  Practice         125 

tion  begins  to  cause  a  rise.  Then  the  ignition  itself  takes  some 
time  to  be  completed,  here  about  ^  second  ;  the  piston  has, 
therefore,  moved  through  a  further  one-and-a-half-tenth  of  its 
stroke  and  the  heat  given  by  the  explosion  is  not  added  at  strictly 
constant  volume,  as  required  by  theory.  Apart  altogecher  from 
loss  of  heat  to  the  cylinder  walls,  this  diagram  is  mechanically  im- 
perfect. The  valve  arrangements  should  be  such  that  no  loss  is 
incurred  in  charging  and  that  the  explosion  follows  so  rapidly  that 
the  pressure  in  the  cylinder  has  no  time  to  fall  by  expansion, 
after  closing  the  admission  ;  the  explosion,  indeed,  should  at  once 
follow  the  cut-off.  In  the  best  of  the  three  lines  the  pressure  has 

2055°  C.  absolute 


i534°C.abs. 


J246-C.  abs. 


FIG.  25.  — Lenoir  Engine  Diagram. 

fallen  to  nearly  1 1  Ibs.  total,  and  the  maximum  pressure  of  the 
explosion  is  48  Ibs.  per  square  inch  total.  The  average  of  the 
three  lines  gives  a  pressure  divided  over  the  whole  stroke  of  only 
8-3  Ibs.  per  square  inch,  which,  assuming  the  diagram  from  the 
other  end  of  the  cylinder  to  give  similar  results,  gives  a  total  ot 
2  indicated  horse  power  at  50  revolutions  per  minute.  This  is 
an  exceedingly  poor  result  for  so  large  an  engine.  The  apparent 
indicated  efficiency  is  much  below  that  of  a  theoretical  diagram 
using  the  same  expansion.  Fig.  25  shows  in  dotted  lines  a 
diagram  which  will  have  the  same  efficiency  as  the  actual  diagram 
(best  of  the  three  lines).  If  the  temperature  of  the  entering 
charge  has  been  raised  to  100°  C.,  as  stated  by  Mr.  Slade,  then 
the  point  c  upon  the  diagram  corresponds  to  that  tempera- 
ture; the  point  d  will  correspond  to  a  temperature  of  2035°  C. 
absolute,  as  the  volume  has  increased  from  0-4  to  0-5  and  the 


128  The  Gas  Engine 

Apparent  indicated  efficiency  x  efficiency  of  gas  =  actual 
indicated  efficiency  : 

0-175  x  °'33  =  °'°58 

The  actual  indicated  efficiency  of  the  engine  is  0*058  or  5-8 
per  cent,  if  this  diagram  be  constantly  repeated;  but  as  it  is  the 
best  of  the  three  lines  it  requires  correction.  Taking  the  worst  of  the 
three  diagrams,  fig.  24  shows  the  temperature  as  follows  :  T,  2035° 
absolute;  T1,  1697°  absolute  ;  /,  797° ;  /',  1-243°  absolute. 

The  apparent  indicated  efficiency  is  E  =  0-126. 

The  actual  indicated  efficiency  is  0*126  x  0-33  =  0-0495  or 
4-95  per  cent,  of  the  total  heat  given  to  the  engine. 

Tresca  calculates  the  heat  transformed  into  work  by  the  Lenoir 
tested  by  him  as  4  per  cent. 

The  mean  of  the  best  and  worst  of  these  diagrams  is 

c-8  4-  4/Qf*; 

2          =5'37, 

which  is  higher  than  the  result  obtained  by  this  distinguished  physi- 
cist ;  but  the  difference  is  sufficiently  accounted  for  by  the  differ- 
ence in  the  dimensions  of  the  engines.  Tresca's  was  only  half- 
horse,  Slade's  was  two  horse. 

The  Lenoir  engine  used  mixtures  ranging  in  composition  from 
i  gas  and  6  vols.  air  to  i  vol.  gas  and  12  vols.  air,  depending  upon 
the  amount  of  work  upon  the  engine ;  when  there  was  little  work 
the  governor  was  arranged  to  throttle  the  gas  and  so  diminish  the 
proportion  present.  This  was  a  bad  plan,  as  will  be  explained  in  the 
chapter  upon  governing.  But  the  effect  was  to  make  the  engine 
use  all  grades  of  ignitable  mixtures  from  the  strongest  to  the 
weakest.  Apart,  however,  from  all  intentional  arrangements  for 
governing,  these  engines  tended  to  govern  themselves.  An  increase 
of  speed  always  causes  the  proportion  of  gas  in  the  mixture  to 
diminish,  because  the  resistance  of  the  small  gas  port  to  flow 
increases  more  rapidly  than  the  larger  air  port.  It  follows  that  if 
the  ports  are  proportioned  to  pass  certain  volumes  at  a  low  rate  of 
speed,  at  a  higher  rate  the  proportion  is  disturbed,  the  smaller 
port  giving  a  greater  proportional  resistance.  The  effect  is  seen 
in  all  the  diagrams,  the  ignitions  become  later  and  later  as  the 
mixture  diminishes  in  inflammability,  and  after  attaining  a  certain 


Gas  Engines  of  Different  Types  in  Practice         1 29 

dilution,  ignition  ceases  altogether,  or  becomes' too  slow  to  be  of 
any  practical  use.  In  the  Lenoir  type  of  engine  too  slow  ignition 
is  an  unmixed  evil,  as  the  theory  of  the  engine  requires  rapid  igni- 
tion. In  it  the  loss  of  efficiency  due  to  valve  and  igniting  arrange- 
ments is  considerable.  The  electric  ignition  is  very  delicate  and 
troublesome.  To  overcome  the  defects  of  the  Lenoir,  Hugon 
introduced  his  engine,  which  in  some  respects  was  a  considerable 
advance. 

HUGON  ENGINE. 

The  Hugon  engine,  like  the  Lenoir,  exploded  the  charge  drawn 
into  the  cylinder  by  the  piston  at  atmospheric  pressure  :  in  it, 
however,  greater  expansion  and  more  dilute  mixtures  were  used. 


FIG.  26.  FIG.  27. 

Hugon  Engine  Cylinder. 

Fig.  26  is  a  sectional  plan  showing  valves,  passages  and  the 
cylinder  and  piston.  Fig.  27  is  a  transverse  vertical  section 
through  the  cylinder  at  the  line  ab.  The  admission  of  the  charge 
and  the  expelling  of  the  exhaust  are  accomplished  through  the 
same  passage,  so  that  the  cylinder  has  only  two  ports,  as  in  the 
steam  engine  ;  two  valves  are  used,  one  working  outside  the  other. 
The  inner  valve  has  five  ports,  two  for  admitting  the  charge,  one 
for  exhausting,  and  two  for  carrying  the  igniting  flame.  The 
ignition  by  flame  was  first  accomplished  in  a  workable  manner  by 
Hugon,  although  it  had  been  described  in  several  patents  long 
before  his  time. 

The  ports  marked  i  i  in  the  inner  slide  A  are  admission,  the 

K 


1 30  The  Gas  Engine 

ports  marked  2  2  in  the  inner  slide  are  igniting,  ports ;  the  port  3 
is  the  exhaust  passage,  alternately  communicating  with  each  end 
of  the  cylinder  by  the  long  ports  4  4  to  the  exhaust  port  5,  pre- 
cisely as  in  a  steam  engine.  The  action  of  the  admission  ports 
is  somewhat  novel.  The  object  is  to  secure  a  rapid  opening  and 
cut-off,  bringing  the  igniting  flame  on  immediately  after  closing 
the  cylinder.  The  valve  is  actuated  from  a  cam.  When  the 
piston  is  at  the  end  of  its  stroke  and  is  moving  forward,  the 
valve  A  is  moving  in  the  same  direction,  the  port  3  is  allowing 
the  exhaust  gases  to  escape  from  the  other  side  of  the  piston,  the 
port  i  is  open  to  the  cylinder  and  is  communicating  through  the 
port  6  or  6,  in  the  outer  slide  B,  with  the  air  and  also  with 
the  gas  supply.  When  the  piston  has  taken  in  sufficient  charge, 
the  cam  moves  the  slide  A  suddenly  forward,  so  causing  the  port  i 
to  close  on  the  outer  side  but  not  on  the  inner ;  the  igniting 
port  comes  on  and  the  flame  burning  in  it  inflames  the  mixture, 
filling  the  engine  port,  from  whence  it  spreads  into  the  cylinder 
itself.  As  the  inner  valve  cuts  off  when  moving  in  the  same 
direction  as  it  does  when  opening,  it  is  evident  that  it  must  cross 
back  again,  to  be  in  the  position  required  to  commence  opening 
at  the  correct  time.  While  crossing,  unless  the  communication 
"with  the  atmosphere  and  gas  supply  is  stopped  in  some  other  way, 
it  will  open  at  the  wrong  time ;  to  prevent  this,  the  outer  valve  B 
is  provided.  It  is  actuated  from  a  pin  projecting  from  the  main 
valve  A  ;  this  pin  7  works  in  the  slot  8,  and  while  the  main  valve 
is  moving  forward  after  cutting  off,  the  pin  strikes  the  end  of  the 
slot  and  carries  the  outer  valve  with  it,  causing  it  to  close  the  port 
in  the  cover  which  it  commands.  A  small  plate  and  spring  give 
friction  enough  to  keep  the  valve  in  position  till  it  is  moved  in 
the  other  direction.  When  the  main  valve  returns,  although  its 
ports  open  on  the  engine  ports,  the  outer  ends  are  blinded  by  the 
outside  valve  which  is  not  again  opened  till  the  main  valve  has 
closed.  By  this  ingenious  contrivance,  a  rapid  admission  and 
cut-off  are  secured  with  one  cam  and  the  main  and  auxiliary 
slides.  The  engine  from  which  these  details  are  taken  is  in  South 
Kensington  Museum  and  is  rated  at  J-horse  power.  The  valves 
are  arranged  to  cut  off  at  about  one-third  stroke. 

The  cylinder  is  8j\  diameter  and  10  in.  stroke.    The  clearance. 


Gas  Engines  of  Different  Types  in  Practice         1 3 1 

spaces  due  to  the  long  ports  4  4,  the  valve  ports  open  to  the 
cylinder  at  the  moment  of  explosion,  and  the  space  into  which  the 
piston  does  not  enter,  make  up  in  all  a  proportion  of  products  of 
combustion  equivalent  to  nearly  thirty  per  cent,  of  the  entire  charge. 
The  effect  of  this  is  to  cause  a  considerable  difference  between 
the  nature  of  the  mixture  in  the  port  and  that  in  the  cylinder 
itself,  the  port  mixture  being  much  more  inflammable  than  that 
in  the  cylinder.  As  a  consequence  the  ignition  is  more  rapid 
with  weak  mixtures  than  in  the  Lenoir.  The  gas  is  supplied  to 
the  air  port  in  regulated  amount  by  means  of  a  bellows  pump 
worked  from  an  eccentric  on  the  crank  shaft ;  it  mixes  with  the  air 
in  passing  through  the  valves  and  port ;  the  products  of  combustion 
are  therefore  completely  expelled  from  the  port,  and  nothing  but 
pure  mixture  left  to  be  inflamed  by  the  igniting  arrangement. 
The  gas  for  the  internal  igniting  flame  is  supplied  also  from  a 
bellows  pump  under  slight  pressure.  This  flame  is  extinguished 
by  each  explosion,  and  is  relighted  when  the  port  cpens  again  to 
the  air  by  a  constant  external  flame.  The  action  of  the  exhaust 
port  in  the  main  slide  is  so  evident  as  to  require  no  other 
explanation  than  that  afforded  by  the  drawing. 

The  engine  works  very  smoothly,  and  is  a  great  improvement 
upon  Lenoir  in  certainty  of  action  ;  all  the  trouble  with  the 
battery  and  coil  is  very  simply  avoided.  To  prevent  overheat- 
ing of  the  piston,  water  is  injected  by  means  of  a  tap ;  it  is 
adjusted  so  that  each  suck  of  the  engine  drawing  in  mixture  also 
takes  in  enough  water  to  keep  the  piston  at  a  reasonable  tempe- 
rature. In  this  the  engine  was  successful  ;  it  was  capable  of 
harder  and  more  continuous  work  than  the  Lenoir,  and  was  in 
every  way  more  certain  in  its  action  even  with  a  considerable 
variation  in  the  composition  of  the  explosive  mixture  used.  The 
only  parts  which  gave  trouble  were  the  bellows  pumps  controlling 
the  gas  supply  to  cylinder  and  igniting  port  ;  these  were  made  of 
rubber,  and  deteriorating  after  some  use  gave  trouble  by  leaking 
and  occasional  bursting.  In  some  of  the  engines  in  use  they 
were  replaced  by  metal  pumps  and  a  mixing  valve.  With  these 
additions  the  engine  in  the  Patent  Office  Museum  ran  for  many 
years. 

Diagrams   and   Gas    Consumption, — According   to   Professor 

K  2 


132 


The  Gas  Engine 


Tresca,  the  gas  consumed  by  a  Hugon  engine  of  2 -horse  power 

was  85  cubic  feet  per  indicated  horse  per  hour. 

Fig.  28  is  a  diagram  taken  from 
a  -|-horse  engine  by  the  author. 
The  engine  was  indicating  078 
horse  power,  the  average  pressure 
being  3^9  Ibs.,  and  the  maximum 
25  Ibs.  per  sq.  in.  The  card  shows 
considerable  delay  in  explosion  after 
cut-off,  notwithstanding  the  rapid 
movement  of  the  igniting  slide. 

BISCHOFF  ENGINE. 

The  consumption  of  the  non- 
compression  type  of  engine  is  too 
high  to  permit  of  its  use  in  any  but 
the  very  smallest  machines  ;  accord- 
ingly the  Lenoir  and  Hugon  engines 
have  long  disappeared  from  the 
market,  and  the  type  survives 
mainly  in  the  BischofT,  which  is 
specially  designed  for  small  powers, 
mostly  under  half-horse.  It  is  an 
exceedingly  ingenious  little  engine, 
and  presents  many  interesting  pe- 
culiarities. 

Fig.  29  is  a  side  elevation,  part 
in  section  ;  fig.  30  a  section  arranged 
to  explain  the  valve  action.  In  both 
figures  the  similar  parts  are  marked 
with  similar  letters.  There  is  no  at- 
tempt to  gain  economy  by  attention 
to  theory  ;  the  aim  is  to  get  a  small 
workable  engine  with  the  least  possible  complication.  In  this  it  is 
very  successful.  To  avoid  the  complication  of  a  water-jacket, 
the  cylinder  and  piston  are  so  arranged  that  heating  is  allowable. 
The  engine  is  upright  and  very  peculiar  in  appearance,  the 
cylinder  has  cast  on  it  a  number  of  radiating  ribs,  which  by 


Gas  Engines -of  Different  Types  in  Practice         133 

contact  with  the  air  cause  conduction  of  the  heat  more  rapidly 
than  would  otherwise  occur.  The  temperature,  however,  becomes 
very  high,  and  provision  is  made  to  prevent  injury  to  the  piston. 
It  is  fitted  loosely  to  the  cylinder  and  has  no  rings,  the  connecting 


FIG.  29. 

Bischoff  Engine. 


FIG.  30. 


rod  arrangement  is  seen  in  the  figure  (29)  ;  it  takes  the  thrust  of  the 
explosion  in  tension,  and  almost  without  side  pressure  upon  the 
guide.  Any  side  pressure  upon  the  guide  is  quite  prevented  from 
reaching  the  piston,  and  it  consequently  is  never  rubbed  against 


134  T he  Gas  Engine 

the  cylinder.  The  pressure  of  the  explosion  is  so  slight  that  the 
leakage  is  not  serious  even  without  rings.  The  piston  moves  up, 
taking  in  the  charge,  the  air  through  the  valve  i,  fig.  30,  which  is 
simply  a  piece  of  sheet  rubber  backed  by  a  thin  iron  disc.  The 
pressure  of  the  air  opens,  and  the  explosion  closes  it ;  the  valve  2, 
fig.  29,  similarly  made  but  smaller,  admits  the  gas ;  the  mixture 
does  not  form  till  the  gases  have  passed  the  point  3,  fig.  30; 
therefore  the  explosion  does  not  spread  back  to  the  valves. 
When  the  piston  gets  to  the  point  4,  it  crosses  a  small  aperture  5 
covered  by  a  light  hanging  valve  ;  a  flame  burning  outside  in  the 
flame  chamber  is  drawn  in.  The  explosion  then  occurs,  and  the 
pressure  at  once  closes  all  valves  and  propels  the  piston.  On  the 
return  stroke,  the  piston  valve  7  opens  to  the  exhaust  pipe  8,  at  the 
same  time  closing  the  passage  to  the  air  admission  valves.  The 
cylinder  proper  requires  no  lubrication;  the  guide  requires  a 


Scale  i  in.  =  24  Ibs.  ;  3^"  diam;  of  cylinder  ;  n£  ins.  stroke. 

P^IG.  31. 
Diagram  from  i-man  power  Bischoff  Engine  ;   112  revs,  per  min.     \Clerk.} 

little,  but  the  projection  of  the  cover  and  a  draining  hole  prevent 
accumulation  and  overflow  of  oil  into  the  cylinder.  This  pre- 
caution is  very  necessary,  because  of  the  high  temperature  of  both 
piston  and  cylinder;  without  it  speedy  charring  and  choking 
up  of  the  cylinder  would  result.  The  arrangements  are  crude 
and  the  engine  is  somewhat  noisy,  but  it  is  very  reliable,  and  suits 
the  purpose  for  which  it  is  designed  exceedingly  well. 

Diagrams  and  Gas  Consumption. — The  diagram  is  very  similar 
to  the  Lenoir.  Fig.  31  is  a  diagram  taken  from  a  i-man  power 
engine  by  the  author. 

The  consumption  is,  as  might  be  expected,  rather  higher  than 
Lenoir.  According  to  tests  made  at  the  Stockport  Exhibition  it 
uses  120  cubic  feet  per  actual  horse  power  per  hour. 


Gas  Engines  of  Different  Types  in  Practice         135 

TYPE  (!A). 

Free  Piston  Engines. — The  very  high  consumption  of  gas 
common  to  the  engines  described  prevented  their  extended  use, 
and  set  inventors  to  work  to  produce  some  method  which  would 
give  better  results.  It  was  very  obvious  that  there  was  a  large 
loss  of  heat ;  the  trouble  with  cylinders  and  pistons  made  this 
abundantly  evident.  Devices  proposed  for  increasing  power  by 
the  injection  of  water  spray,  and  steam,  in  various  ways  failed 
to  produce  good  effect  except  in  aiding  lubrication.  The  inventors 
of  the  day  seem  to  have  reasoned  somewhat  in  this  fashion.  The 
force  generated  by  an  explosion  of  gas  and  air  is  an  exceedingly 
evanescent  one,  a  high  pressure  is  produced,  but  it  lasts  only  for 
a  very  short  time ;  if  work  is  to  be  obtained  before  loss  by 
cooling  absorbs  all  the  heat,  it  must  be  done  rapidly.  The 
reason  why  the  Lenoir  and  Hugon  engines  give  so  poor  a  result 
is  a  too  slow  movement  of  piston  after  the  explosion.  Therefore, 
if  a  method  can  be  devised  permitting  greater  piston  velocity, 
better  economy  will  be  obtained.  In  this  reasoning  there  was 
considerable  truth.  It  has  been  already  proved  that  the  shorter 
the  time  of  contact  between  the  charge  after  explosion  and  the 
enclosing  walls,  the  greater  will  be  the  efficiency  of  the  gas  in  the 
mixture.  But  this  only  holds  within  certain  limits.  If  the  expan- 
sion is  too  rapid  before  explosion  is  complete,  then  a  loss  instead 
of  a  gain  will  occur ;  the  expansion  should  not  commence  till 
maximum  pressure  is  attained  or  it  will  cause  a  loss  of  pressure. 
Indeed,  it  is  quite  conceivable  that  in  engines  of  the  Lenoir  type, 
the  expansion  might  be  so  rapid,  relatively  to  the  rate  of  explosion, 
that  no  increase  of  pressure  at  all  resulted  ;  in  which  case  no  power 
whatever  would  be  obtained.  The  gain  then  to  be  expected 
arises  from  rapid  expansion  after  complete  explosion.  This  has 
been  carried  out  by  several  inventors  by  the  free  piston  method. 
Instead  of  expending  the  force  of  the  explosion  upon  a  piston 
rigidly  connected  to  a  crank,  the  piston  is  allowed  free  movement. 
The  explosion  launches  it  against  the  atmosphere  ;  it  acquires 
considerable  velocity,  which  is  expended  in  compressing  the 
exterior  atmosphere,  that  is,  in  producing  a  vacuum  in  the  cylinder. 
When  all  the  energy  of  motion  is  expended,  the  piston  comes  to 


1 36  The  Gas  Engine 

rest,  and  the  atmospheric  pressure  forces  it  back  again.  So  soon 
as  the  return  movement  commences,  a  clutch  contrivance  engages 
the  shaft  and  drives  it.  Engines  of  type  i  A  may  be  described  as— 

Engines  using  a  gaseous  explosive  mixture  at  atmospheric 
pressure  before  explosion  ;  the  explosion  acting  on  a  piston  free  to 
move  without  connection  with  the  crank  shaft,  the  velocity  being 
absorbed  by  the  formation  of  a  vacuum.  The  power  is  given  to 
the  shaft  on  the  return  stroke  under  the  pressure  of  the  atmo- 
sphere. 

As  has  been  stated  in  the  historical  sketch,  the  first  to  propose 
this  kind  of  engine  were  Barsanti  and  Matteucci,  1857,  but  the 
difficulties  were  not  sufficiently  overcome  until  the  invention  of 
Otto  and  Langen,  1866. 

Otto  and  Langen  Engine. — This  engine  consists  of  a  tall  vertical 
cylinder  surrounded  by  a  water  jacket  ;  in  it  works  a  piston  which 
carries  a  rack  instead  of  a  piston  rod;  the  mouth  of  the  cylinder  is 
open  to  the  atmosphere.  Across  the  top  of  the  cylinder  is  carried 
the  fly-wheel  shaft  ;  it  cannot  be  called  the  crank  shaft  because 
there  is  no  crank.  On  the  shaft  there  is  a  toothed  wheel  which 
engages  the  teeth  of  the  rack  ;  it  runs  freely  on  the  shaft  while  the 
piston  is  on  its  upward  stroke,  but  by  an  ingenious  clutch  arrange- 
ment it  grips  the  shaft  when  the  piston  moves  down.  The  shaft  is 
therefore  free  to  rotate  in  one  direction  and  the  piston  is  free  to 
move  up  without  restraint,  but  in  moving  down  it  gives  the  impulse. 
The  shaft  is  carried  on  bearings  bolted  to  the  top  of  the  cylinder, 
which  forms  a  strong  and  convenient  column  for  carrying  the 
mechanism  required  to  accomplish  the  cycle  of  the  engine.  At 
the  lower  end  of  the  column  is  placed  a  slide  valve  which  performs 
the  treble  duty  of  admitting,  igniting,  and  discharging.  It  is  driven 
from  an  intermediate  shaft,  intermittently,  as  determined  by  the 
governor  of  the  engine.  When  working  at  full  load,  the  move- 
ment of  a  small  crank  actuated  from  the  shaft,  lifts  the  rack  and 
piston  through  some  inches,  taking  in  the  charge  through  the  slide 
valve,  which  then  moves  further  and  brings  in  the  igniting  flame. 
The  explosion  ensues  and  shoots  up  the  piston  with  consider- 
able velocity,  the  pressure  rapidly  falls  by  expansion  and  soon 
gets  to  atmosphere.  The  piston  however  has  been  moving  freely 
and  therefore  has  done  no  work  ;  all  the  energy  of  the  explosion, 


Gas  Engines  of  Different  Types  in  Practice         137 

however,  has  been  given  to  it.  The  piston  has  the  energy  of  explosion 
in  the  form  of  velocity  ;  it  moves  on,  the  pressure  beneath  it  falling 
below  atmosphere  until  all  its  energy  of  motion  is  absorbed  in 
forming  the  vacuum.  When  this  occurs  it  ceases  its  upward  flight 
and  returns,  the  outer  atmosphere  driving  it  back,  and  as  the  clutch 
has  engaged  the  shaft,  an  impulse  is  given.  The  actual  work  is 


FIG.  32. — Otio  and  Langen  Engine  (vertical  section). 

therefore  done  by  the  atmosphere  on  the  down  stroke,  the  explosion 
being  spent  in  obtaining  energy  in  a  form  conveniently  applic- 
able. If  no  cooling  of  the  hot  gases  occurred  upon  the  down 
stroke  the  compression  line  would  return  to  the  point  where  the 
expansion  line  touched  atmosphere  ;  then  the  exhaust  valve  would 
open  and  the  gases  would  be  discharged  at  atmospheric  pressure. 


138  The  Gas  Engine 

In  that  case  the  work  done  by  the  atmosphere  and  weight  of  piston 
on  the  downward  stroke  would  exactly  equal  the  energy  of  the  ex- 
plosion while  falling  by  expansion  to  atmospheric  pressure.  But  the 
cylinder  does  cool  the  gases  while  on  the  upward  and  downward 
stroke,  so  that  the  expansion  line  does  not  return  upon  itself  ;  the 
amount  of  fall  below  the  expansion  line  is  gain  and  is  added  to  the 
energy  of  the  explosion  just  as  the  condenser  adds  to  the  efficiency 
of  the  expansion  of  steam.  The  exhaust  gases  are  expelled  by  the 
piston  and  a  new  stroke  is  commenced.  At  full  power  the  piston 
makes  about  30  strokes  per  minute,  the  shaft  rotating  about  90 
revolutions  per  minute.  The  governor  of  the  engine  is  so  arranged 
that  when  the  speed  becomes  too  great,  a  lever  disengages  a  pawl 
from  a  ratchet  and  disconnects  the  small  crank  lifting  the  piston. 
The  charge  is  not  taken  in  till  the  speed  falls,  and  then  the  pawl 
is  again  allowed  to  connect  the  small  crank  to  the  main  shaft. 
The  ignition  slide  gets  its  motion  from  the  small  crank  shaft,  so  that 
it  is  arrested  or  moved  along  with  the  piston.  The  piston 
remains  at  the  bottom  of  the  stroke  till  it  is  wanted  for  another 
explosion. 

Fig.  9,  p.  21,  shows  the  general  arrangement  of  the  engine,  and 
Tig  32  is  a  vertical  section  showing  the  clutch  and  section  of  the  slide 
valve.  Fig.  33  is  an  elevation,  part  in  section. 

A  is  the  cylinder  ;  B  is  the  piston  to  which  is  attached  the 
rack  c  ;  D  the  toothed  wheel  containing  the  clutch  engaging 
the  rack  to  the  power  shaft.  The  rack  is  strongly  guided.  E  is 
the  fly-wheel  shaft  on  which  is  keyed  the  fly  wheel  F  and  the 
driving  pulley  G  ;  H  water  jacket ;  I  the  port  for  inlet  of  the 
explosive  mixture  and  discharge  of  the  products  of  combustion  ; 
K  the  slide  valve  serving  to  admit,  to  ignite  the  charge  and  to  dis- 
charge the  products  of  combustion  ;  it  is  actuated  from  the  small 
shaft  L  by  the  pin  M  ;  the  ratchet  N  and  the  pawl  o  connect  the 
small  shaft  to  the  main  shaft  when  requisite,  as  determined  by  the 
governor  lever  p. 

This  engine  is  the  result  of  great  care  and  labour  on  the  part 
of  the  inventors;  it  is  greatly  superior  in  economy  and  efficiency 
to  any  preceding  it,  and  its  only  fault  is  its  excessive  bulk  and 
weight  and  the  great  noise  made  by  it  when  in  action.  The  whole 
of  the  energy  of  the  explosion  being  expended  in  giving  the  piston 


UNIVJuRdlT 


Gas  Engines  of  Different  Types  in  Practice         139 

velocity,  just  as  in  a  cannon,  the  recoil  is  considerable.  So 
serious  is  it  that  none  but  the  very  smallest  engines  can  be  placed 
upon  upper  floors  without  special  strengthening.  The  author  has 
seen  an  engine  at  work  where  the  vibration  produced  was  so  great 
that  props  were  put  under  the  engine  from  floor  to  floor  through 
four  floors  to  get  a  solid  resistance  in  the  basement. 


FIG.  33.  — Otto  and  Langen  Engine  (elevation). 

In  other  cases  strong  iron  beams  placed  diagonally  at  the  angle 
of  a  stone  wall  carried  the  engine;  notwithstanding  these  precau- 
tions much  vibration  was  caused.  These  difficulties  did  not 
seriously  affect  the  sale  of  the  engine  for  small  powers,  but  they 
quite  prevented  it  being  made  for  powers  above  3-horse.  The 
clutch  also  is  a  matter  of  great  difficulty,  the  whole  power  of  the 


140 


The  Gas  Engine 


engine  passes  through  it  and  it  must  act  freely  and  instantaneously. 
The  faintest  back  lash  would  allow  the  accumulation  of  so  much 
velocity  by  the  return  that  even  a  strong  arrangement  would  be 
destroyed.  For  this  reason  the  pawl  and  ratchet  of  Barsanti  and 
Matteucci  failed  completely. 


Messrs.  Otto  and  Langen's  clutch  is  one  of  the  main  points  of 
their  invention  and  is  excellent.  It  is  shown  in  detail  at  fig.  34. 
The  part  a  is  keyed  to  the  shafi;  on  it  runs  the  part  b  carrying 


Gas  Engines  of  Different  Types  in  Practice         141 

the  teeth  engaging  the  rack.  So  long  as  b  moves  in  the  direction 
of  the  arrow  i,  or  is  stationary,  a  revolves  freely  with  the  shaft  in 
the  direction  2.  The  steel  slips  c,c,c,c  are  wedge-shaped  on  the 
back,  so  is  the  interior  of  the  part  b  at  the  positions  d,  d,  d,  d. 
So  long  as  the  rack  is  stationary  or  ascending,  the  steel  rollers 
e,e,e,e,  run  freely  clear  of  the  inclined  surfaces  ;  immediately  the 
rack  moves  down  at  a  rate  greater  than  the  movement  at  A,  then 
the  rollers  are  firmly  wedged  between  the  two  inclined  surfaces 
and  the  steel  slips  c,  c,  c,  c  grip  the  part  a  firmly  and  drive  the 
shaft.  When  the  bottom  of  the  stroke  is  reached  the  wedges  loose 
again  and  the  piston  is  free. 

Diagrams  and  Gas  Consumption. — The  author  has  made  a  set 
of  experiments  upon  an  engine  of  2-horse  power  working  with 
Oldham  coal  gas. 

The  cylinder  is  12*5  inches  diameter  and  the  longest  stroke 
observed  was  40*5  inches.  Working  at  the  rate  of  28  ignitions 
per  minute,  the  indicated  power  was  2*9  horse,  and  the  gas  was 
consumed  at  the  rate  of  24-6  cubic  feet  per  i.h.p.  per  hour.  The 
brake  power  is  2  horse,  so  that  the  brake  consumption  is  at  the 
rate  of  36  cubic  feet  per  horse  power  per  hour.  This  does  not 
include  the  consumption  of  the  side  lights  which  is  in  all  12  cubic 
feet  per  hour. 

Fig.  35  is  a  diagram  from  the  engine  when  at  full  power. 

The  full  line  is  that  traced  by  the  indicator,  and  the  dotted 
line  is  the  real  line  of  pressures  marred  by  the  oscillation  of  the 
indicator  pencil. 

Professor  Tresca.  tested  a  half-horse  engine  at  the  Paris  Ex- 
hibition of  1867;  it  gave  0-456  brake  horse,  and  consumed  gas  at 
the  rate  of  44  cubic  feet  per  brake  horse  power  per  hour.  This  es- 
timate did  not  include  the  side  lights.  The  author's  test  gives  a 
better  result  than  that  of  M.  Tresca,  but  this  is  due  to  the  fact  of 
the  larger  engine  being  used.  It  is  probable  that  a  3 -horse  engine 
would  give  a  consumption  of  about  30  cubic  feet  per  brake  horse 
power  per  hour. 

The  interest  excited  by  the  engine  at  the  time  of  its  first  trial 
was  naturally  great,  and  many  explanations  were  advanced  of  the 
cause  of  its  superiority  over  the  Lenoir  and  Hugon  engines. 
Strangely  enough  the  theory  of  the  engine  has  been  at  best  but 


142 


The  Gas  Engine 


imperfectly  stated  by  previous  writers;  some  indeed  have  fallen 
into  grave  error  respecting  its  action.  It  is  therefore  essential 
that  it  should  be  somewhat  fully  considered  here. 


The  name  by  which  it  is  most  widely  known  is  in  itself  mis- 
leading. Atmospheric  gas  engine  at  once  suggests  the  Newcomen 
steam  engine  and  further  suggests  the  substitution  of  flame  for 


Gas  Engines  of  Different  Types  in  Practice         143 

steam,  vacuum  in  both  cases  being  supposed  to  be  produced  by 
condensation.  In  the  steam  engine  the  name  truly  describes  the 
action  :  the  piston  is  drawn  up,  the  cylinder  filled  with  steam  at 
atmospheric  pressure  and  the  steam  condensed  by  a  water  jet ; 
then  the  atmosphere  presses  the  piston  down  and  gives  the  power. 

In  the  gas  engine  cooling  has  little  to  do  with  the  production 
of  the  vacuum  ;  the  vacuum  would  be  produced  and  the  engine 
would  act  efficiently  without  any  cooling  action  of  the  cylinder 
whatever.  The  diagram  fig.  35  proves  this  very  clearly.  While 
the  piston  is  moving  from  the  point  a  to  b  by  the  energy  stored 
up  in  the  fly  wheel,  the  charge  enters  the  cylinder;  at  b  the  piston 
pauses,  and,  the  igniting  flame  being  introduced,  the  charge  ex- 
plodes, the  pressure  rises  to  54  Ibs.  per  square  inch  above  atmo- 
sphere. The  appearance  of  the  explosion  curve  does  not  indicate 
truly  the  rate  of  increase,  because  the  piston  is  completely  at  rest 
till  the  pressure  puts  it  in  motion.  The  piston  moves  up  impelled 
by  the  pressure  of  the  explosion;  as  it  moves  the  gases  beneath  it 
expand  and  therefore  the  pressure  falls.  At  the  point  d  the  pres- 
sure is  again  level  with  that  of  the  outside  atmosphere;  here  the 
explosion  ceases  to  impel  the  piston  and,  the  pressure  in  the  cy- 
linder falling,  the  atmosphere  presents  a  continually  increasing 
resistance.  But  while  the  piston  is  passing  from  the  point  b  to  d, 
the  pressure  has  been  falling  from  54  Ibs.  above  atmosphere  to 
atmosphere ;  the  average  pressure  upon  it  through  this  distance  is 
1 2 '6  Ibs.  per  square  inch;  as  the  distance  is  i '3 feet  and  the  piston 
area  is  122*7  inches,  2010  ft.  pounds  have  been  expended  upon  it. 
What  becomes  of  this  work  ?  In  an  ordinary  engine  it  would  be 
communicated  to  the  crank,  and  if  no  load  were  on,  the  crank 
would  give  it  to  the  fly  wheel.  Here  there  is  no  crank  and  the 
piston  is  perfectly  free,  the  piston  alone  contains  the  energy  ;  its 
weight  has  been  raised  through  i  -3  feet  and  the  balance  of  the 
energy  is  stored  in  it  as  velocity  of  upward  movement. 

It  must  therefore  continue  to  move  up  till  its  energy  of  motion 
is  expended  in  compressing  the  atmosphere,  in  raising  the  piston, 
and  in  friction.  If  friction  did  not  exist  and  the  piston  was  indefi- 
nitely light,  then  the  portion  of  the  diagram  bed  would  be  equal 
in  area  to  the  portion  def,  that  is,  the  work  expended  by  the  ex- 
plosion in  giving  the  piston  velocity  would  be  equal  to  the  work 


144  ^*  Gas  Engine 

expended  by  the  atmosphere  in  bringing  it  to  rest  again.  Once 
at  rest  the  vacuum  produced  allows  the  piston  to  be  driven  down 
again,  this  time  to  give  up  its  energy  to  the  motor  shaft. 

As  the  piston  in  this  engine  weighs  116  Ibs.  the  work  spent  in 
raising  it  through  1*3  ft.  is  116  x  1-3  =  150-8  ft.  pounds;  deduct 
this  from  the  total  work;  and  2010  —  151  =  1859  ft.  Ibs.  is  the 
energy  of  motion  of  the  piston. 

The  relation  between  energy,  mass  and  velocity  is 


E  =  energy  in  absolute  units.     One  foot  pound  —  32  absolute 
units. 

M  =  mass  in  pounds. 

v  —  velocity  in  feet  per  second. 

The  velocity  is  therefore  v  =  A  /  2E 

V        M 

and 

E  =  1859  x  32  =  59488  absolute  units. 


M=    116  v  =  ^*  *™£—  =  32  nearly. 

The  velocity  of  the  piston  at  the  moment  when  the  explosion 
pressure  has  been  expended  and  the  internal  and  external  pressures 
exactly  balance  is  32  ft.  per  second  or  1560  ft.  per  minute;  at  no 
point  of  the  stroke  in  any  ordinary  engine,  steam  or  gas,  is  such  a 
high  piston  speed  possible.  This  explains  the  recoil  of  the  engine. 
But  this  is  not  the  average.  The  piston  has  attained  32  feet  per 
second  after  moving  through  i  -3  feet  ;  the  time  taken  to  move  that 

distance  is  /  =        /«  when  /  =  time  in  secOnds. 
V     v 

s  =  space  passed  through. 
v  =  velocity. 
and  s  =  1-3  feet  v  =  32  feet. 


/  —  /   2  X  I' 

*  — 


=  0-28  second. 


32 

The  piston  has  taken  0-28  second  to  move  through  .the  1-3 
feet  ;  its  average  velocity  during  the  action   of  the  explosion  is 


Gas  Engines  of  Different  Types  in  Practice         145 

therefore  4*64  feet  per  second  or  278  feet  per  minute.  This, 
although  high,  is  not  greatly  in  excess  of  that  used  in  the  Lenoir 
and  Hugon  engines.  It  is  less,  indeed,  than  the  average  piston 
speed  now  used  in  modern  compression  engines,  300  to  400  feet 
per  minute  being  common.  If  no  cooling  by  the  cylinder  occurred, 
the  line  cdf  would  be  adiabatic,  and  the  return  line  fg  would 
coincide  with  the  expansion  line  df\  the  portion  of  the  vacuum 
diagram  def\<s>  due  solely  to  the  energy  of  the  explosion,  the  part 
dfg  is  due  to  the  cooling  of  the  gases.  If  cooling  did  not  act  at 
all,  the  area  bed  would  be  greater,  and  therefore  def,  which  is  its 
equivalent,  would  also  be  greater,  that  is,  the  vacuum  produced 
would  be  greater  if  no  cooling  whatever  existed. 

The  theory  of  its  action  generally  held  at  the  time  of  M.  Tresca's 
experiments  seems  to  have  been  as  follows  : 

The  work  of  the  explosion  consists  simply  in  pushing  up  the 
piston  and  filling  the  space  behind  it  with  flame,  which  flame  is 
cooled  by  contact  with  the  cylinder,  and  a  vacuum  results.  The 
flame  is  considered  as  analogous  to  steam,  and  the  cooling  as 
similar  to  condensation  as  in  the  Newcomen  engine.  The  inven- 
tors of  the  engine  seem  to  share  this  erroneous  idea  ;  certainly 
M.  Tresca  did,  as  in  his  report  upon  the  engine  he  says  :  '  There 
is,  therefore,  between  the  older  machines  and  the  new  one  this 
difference  of  principle,  that  the  pressure  in  the  cylinder  can  never 
descend  below  the  atmospheric  during  the  upward  stroke.  The 
negative  force  of  the  atmospheric  pressure,  useless  as  it  was,  be- 
comes utilisable.  .  .  .'  He  clearly  considered  that  the  pressure 
during  the  upward  stroke  was  expended  only  in  lifting  the  pistcn 
through  a  certain  height,  and  as  soon  as  it  fell  to  atmosphere  the 
piston  stopped  and  the  cooling  caused  a  vacuum,  the  work  being  done 
by  the  falling  of  the  piston  and  the  pressure  of  the  exterior  air. 
If  the  cooling  really  caused  the  vacuum,  the  diagram  would  be 
quite  different  ;  instead  of  the  pressure  touching  atmosphere  at  the 
point  d,  it  would  not  touch  till  the  point  e  at  the  end  of  the  stroke. 
The  pressure  would  then  abruptly  fall  to  /  and  the  piston  would 
return.  M.  Tresca  observed  that  the  pressure  did  fall  below 
atmosphere  before  the  end  of  the  stroke,  but  he  considered  it  as  a 
defect.  '  In  reality  the  piston  rises  in  virtue  of  the  swiftness  ac- 
quired to  beyond  the  position  at  which  there  would  be  equilibrium 


146  The  Gas  Engine 

between  the  interior  and  exterior  pressure.  But  that  one  small 
loss  of  power  is  amply  compensated  for  by  the  atmospheric  power 
of  the  downward  stroke.' 

The  very  principle  of  the  engine  really  depends  upon  this  fall 
of  pressure  which  was  considered  by  M.  Tresca  a  defect ;  it  is  the 
only  way  to  store  up  the  power  of  the  explosion  so  that  it  may  be 
available  on  the  downward  stroke.  If  the  pressure  did  not  fall, 
the  piston  would  require  to  be  projected  10*5  feet  into  the  air  to 
absorb  the  energy  of  the  explosion  in  its  mass  alone  ;  by  the  fall 
of  pressure  it  is  absorbed  with  the  smaller  movement  of  i'8  feet 
The  only  part  of  the  diagram  due  to  cooling  is  the  part  dfg,  not 
more  than  one- fifth  of  the  total  area  representing  work  done  by 
the  engine. 

The  superior  economy,  it  is  evident,  cannot  be  altogether  due  to 
greater  piston  velocity  ;  the  piston  velocity,  although  considerable, 
is  not  superior  enough  to  that  of  Lenoir  and  Hugon  to  account 
for  all  the  difference.  There  must  exist  other  points  of  dissimi- 
larity. In  the  Lenoir  type  of  engine  the  strokes  were  numerous 
and  the  gas  consumed  per  stroke  on  the  whole  smaller  than  in 
Otto  and  Langen  engines  of  equal  power  :  the  latter  used  few 
strokes  but  large  cylinders  ;  proportionally  the  cooling  surface 
exposed  was  thus  diminished.  Then  the  piston  is  at  rest  until 
the  explosion  puts  it  in  motion  ;  the  pressure  gets  time  to  rise  to 
its  maximum  before  the  piston  moves  and  expands  the  space. 
Maximum  pressure  is  attained  at  constant  volume  as  required  by 
theory  ;  at  the  same  time  the  piston  and  cylinder  remain  cool  be- 
cause of  the  infrequency  of  the  strokes.  The  entering  charge  is 
therefore  but  slightly  heated  before  explosion,  and  the  explosion 
gives  a  betier  pressure  for  a  smaller  elevation  of  temperature.  "' 

The  most  potent  cause  of  improvement,  however,  is  great  ex- 
pansion :  the  large  cylinders  allow  an  expansion  of  10  times  the 
volume  existing  before  explosion,  and  so  gain,  first  by  expanding 
to  atmosphere,  and  second  by  the  cooling  which  lollows  the  further 
expansion.  A  comparison  of  the  actual  diagram  with  the  theo- 
retical reveals  some  interesting  peculiarities  which  seem  hitherto 
to  have  escaped  observation.  The  maximum  pressure  on  the 
diagram,  which  is  above  the  true  pressure,  %:3S,  is  54  Ibs.  above 
atmosphere,  corresponding  to  a  temperature  -of  1355°  absolute. 


Gas  Engines  of  Different  Types  in  Practice         147 

The  mixture  exploded  contains  i  volume  gas  and  7  volumes  air 
(Oldham  gas) ;  if  all  the  heat  present  had  been  evolved  by  the 
explosion  the  pressure  should  have  been  168  Ibs.  above  atmo- 
sphere. At  the  maximum  pressure  only  32  per  cent,  of  the  heat  has 
been  evolved,  leaving  68  per  cent,  to  be  evolved  during  the  ex- 
pansion. The  line  cd  is  very  much  above  the  adiabatic,  so  much 
so  that  the  curve  cd  is  nearly  isothermal,  the  temperature  at  d  only 
becoming  1305°  absolute  instead  of  733°,  which  it  should  be  if  adia- 
batic. The  heated  gases  are  therefore  gaining  heat  from  c  to  rf,  and 
as  the  only  source  is  combustion,  it  follows  that  the  combination 
is  not  nearly  complete  at  the  maximum  pressure.  The  68  per  cent. 


Scale  i  in.  =  24  Ibs.     Diluted  mixture,  gas  i  vol.,  air  12  vols. 
FIG.  36. — Diagram  from  2  h.  p.  Otto  and  Langen  Engine  (Clerk). 

of  the  total  heat  which  has  not  appeared  at  the  maximum  pressure 
is  appearing  during  the  expansion.  The  combustion  seems  to  be 
nearly  complete  at  the  point  d  as  the  line  de  behaves  as  if  cooling  ; 
if  adiabatic,  the  temperature  at/should  be  961° — it  is  870°.  During 
compression  to  atmosphere  again,  the  temperature  remains  con- 
stant at  870°  ;  the  cooling  power  of  the  cylinder  is  equal  only  to 
preventing  increase  which  would  otherwise  occur. 

This  effect  is  more  evident  with  a  more  dilute  mixture.    Fig.  36 
is  a  diagram  taken  by  the  author  from  the  same  engine,  but  using 

L  2 


148 


The  Gas  Engine 


a  mixture  containing  i  volume  of  gas  and  1 2  vommes  of  air.  Here 
the  maximum  pressure  is  only  17  Ibs.  per  square  inch  above  atmo- 
sphere. With  complete  evolution  of  heat  it  should  be  103  Ibs. ;  the 
maximum  pressure  in  this  case  only  accounts  for  24  per  cent,  of  the 
heat  known  to  be  present,  leaving  76  per  cent,  to  be  evolved  during 
expansion.  The  diagram  affords  the  most  ample  proof  that  the 

90 


jo- 


50- 


40- 


jo  20  30  40  50  60  70 

Percentage  of  stroke. 


i4'7 


90  loo 


FIG.  37.— Otto  and  Langen  Engine.     Free  Piston. 

combustion  is  proceeding,  the  falling  line  shows  a  steady  increase 
of  temperature  to  the  very  end  of  the  stroke.  The  temperatures 
are  marked  upon  the  diagram  at  the  successive  points  ;  taking  the 
temperature  at  the  point  b  as  290°  absolute,  the  points  t,  d,  e,J,g,  h 
are  respectively  780°,  936°,  1092°,  1107°,  1160°,  and  1225°,  show- 
ing a  steady  increase  throughout  the  whole  expansion  line,  right 


Gas  Engines  of  Different  Types  in  Practice         149 

to  the  end  of  the  stroke.  The  consumption  of  gas  per  indicated 
HP  rises  very  much  in  consequence,  amounting  to  about  37  cubic 
feet  per  I  HP  hour.  The  power  at  the  same  time  falls,  so  that 
the  30  explosions  per  minute  are  required  to  keep  the  engine  going 
without  load  at  53  revolutions  per  minute.  The  cooling  during 
compression  is  so  slow  that  the  temperature  falls  only  from  1225° 
to  967°,  from  the  point  h  to  k.  All  the  published  diagrams  examined 
by  the  author  show  this  peculiar  effect.  Fig.  37  is  a  diagram  pub- 
lished by  Mr.  F.  W.  Crossley.  Taking  80  Ibs.  as  the  maximum  pres- 
sure, which  seems  somewhat  higher  than  is  warranted  by  the  dia- 
gram, the  oscillation  of  the  indicator  has  been  so  excessive,  the  cor- 
responding temperature  is  1873°  absolute  :  the  expansion  line  c  d  if 
adiabatic  would  give  at  the  point  d  a  temperature  of  1090°,  the 
actual  temperature  is  1044°.  Within  the  limits  of  error  they  may 
be  considered  the  same  ;  there  is  therefore  combustion  going  on 
from  c  to  d  also.  At  the  point  e  the  temperature  is  788°  ;  if  adia- 
batic it  should  be  667°.  It  is  quite  evident  that  the  whole  of  this 
expansion  curve  is  above  the  adiabatic  ;  in  the  earlier  part  of  the 
diagram  the  oscillation  causes  uncertainty,  but  in  the  latter  part 
the  measurement  is  true  enough. 

The  compression  line  eg  is  almost  isothermal,  788°  at  e,  cooling 
to  737°  at  g. 

Fig.  38  is  a  diagram  by  Releaux  taken  from  Schottler. 

It  is  manifestly  wrong,  as  the  vacuum  part  is  much  too  small 
and  the  maximum  temperature  is  higher  than  has  ever  been  ob- 
tained by  any  explosion  of  gas  and  air,  but  if  taken  as  relatively 
correct  the  expansion  line  is  much  above  the  adiabatic. 

From  his  study  upon  the  explosion  of  gas  and  air  mixtures  in 
closed  vessels,  the  reader  will  be  prepared  to  find  that  only  a 
portion  of  the  total  heat  present  is  evolved  by  explosion  in  any 
gas  engine.  That  is,  the  explosion  maximum  pressure  never  accounts 
for  the  whole  heat  present  as  inflammable  gas  ;  a  portion  is  in  some 
manner  suppressed  and  is  not  evolved  till  long  after  the  moment 
of  complete  explosion.  Combustion  is  not  completed  till  con- 
siderably after  the  completion  of  explosion. 

He  will  be  unprepared,  however,  for  such  diagrams  as  figs.  35 
and  36,  where  the  maximum  pressure  represents  only  0-32  and  0-24 
of  the  heat  present,  and  0*68  and  076  are  evolved  during  the  forward 


15  o  The  Gas  Engine 

stroke  while  the  pressure  is  falling.  The  explanation  is  simple* 
The  case  is  quite  different  from  that  of  the  closed  vessel  or  where 
the  piston  is  connected  to  a  crank.  As  soon  as  the  pressure,  of 
the  explosion  becomes  great  enough,  the  piston  at  once  moves  out 
and  prevents  further  increase  of  pressure.  The  slower  the  rate  at 
which  the  mixture  inflames,  the  greater  will  be  the  apparent  sup- 
pression of  heat ;  thus  the  mixture  i  volume  gas  7  air  takes,  in  the 
closed  vessel,  0-06  second  to  complete  the  explosion,  but  before  this 


FIG.  38. — Otto  and  Langen. 

time  has  elapsed  the  piston  is  in  rapid  motion  reducing  the  pressure 
before  complete  explosion.  To  get  the  maximum  pressure  it 
would  be  necessary  to  prevent  it  from  moving  till  the  explosion 
was  complete.  The  weaker  mixture  takes  0-25  second  to  complete 
the  explosion,  and  so  in  diagram,  fig.  36,  the  temperature  actually 
rises  throughout  the  whole  stroke. 

A  heavier  piston  would  be  longer  in  starting  under  the  pressure 
of  the  explosion  and  would  so  allow  a  high  pressure  to  be  attained 


Gas  Engines  of  Different  Types  in  Practice         151 


FREE  flSTOJf 


with  a  given  mixture.  This  explains  Mr.  Crossley's  remark  in  reading 
his  paper,  that  heavy  pistons  gave  a  more  economical  result  than 
light  ones. 

Gilles  Engine.—  The  great 
success  of  the  Otto  and  Lan- 
gen  engine  occasioned  many 
attempts  to  improve  upon 
it.  Its  merits  and  its  faults 
were  equally  evident.  The 
recoil  of  the  engine  at  every 
stroke  was  exceedingly  trouble- 
some, and  the  noise  of  the  rack 
and  clutch  could  be  heard  at 
a  long  distance.  Gilles  of  Co- 
logne invented  an  engine  in- 
tended to  retain  the  economy 
while  reducing  the  noise.  In 
it  there  are  two  pistons,  one 
free,  the  other  connected  to  the 
crank  in  the  usual  way.  The 
free  piston  being  at  the  bottom 
of  its  stroke  and  close  to  the 
crank  piston,  the  latter  moves 
a  portion  of  its  stroke,  taking 
in  the  explosive  charge  ;  at  a 
suitable  position  ignition  oc- 
curs and  the  free  piston  is 
driven  in  one  direction  while 
the  other  completes  its  out- 
stroke.  A  vacuum  is  pro- 
duced  between  the  pistons, 
and  the  free  piston  rod  being 
gripped  by  a  clutch  is  kept  in 
its  extreme  position  till  the 
main  piston  returns  under  the 
pressure  of  the  atmosphere.  FlG  39._Gilles  Engine.  Free  Piston. 
The  clutch  is  then  released  and 
the  free  piston  falls,  expelling  the  exhaust  gases.  Fig.  39  is  a 


152  The  Gas  Engine 

section  of  the  engine.  It  is  unnecessary  to  give  further  descrip- 
tion, as  the  engine  was  not  so  economical  or  so  simple  as  the 
earlier  one. 

TYPE    II. 

In  engines  of  this  kind  compression  is  used  previous  to 
ignition,  but  the  ignition  is  so  arranged  that  the  pressure  in  the 
motor  cylinder  does  not  become  greater  than  that  in  the 
compressing  pump.  The  power  is  generated  by  increasing 
volume  at  a  constant  pressure.  Engines  of  Type  II.  are  there- 
fore : 

Engines  using  a  mixture  of  inflammable  gas  and  air  compressed 
before  ignition  and  ignited  in  such  a  manner  that  the  pressure 
does  not  increase,  the  power  being  generated  by  increasing 
volume. 

These  engines  are  truly  slow  combustion  engines  ;  in  them  there 
is  no  explosion. 

The  most  successful  engine  of  the  kind  is  an  American  invention; 
although  proposed  in  1860  by  the  late  Sir  William  Siemens,  it  was 
never  put  into  practicable  workable  shape  till  1873,  when  the 
American,  Brayton  of  Philadelphia,  produced  his  well-known 
machine. 

Messrs.  Simon  of  Nottingham  introduced  it  into  this  country  in 
1878.  They  added  one  thing  only  of  doubtful  utility — that  is,  the 
use  of  steam  raised  in  the  water  jacket  as  auxiliary  to  the  flame  in 
the  motor  cylinder. 

Brayton  Engine. — In  this  engine  there  are  two  cylinders,  com- 
pressing pump  and  motor.  The  charge  of  gas  and  air  is  drawn 
into  the  pump  on  the  out-stroke  and  compressed  on  the  return 
into  a  receiver  ;  the  pressure  usual  in  the  receiver  varies  from  60 
to  80  Ibs.  per  square  inch  above  atmosphere.  The  motor  cylinder 
takes  its  supply  from  the  receiver  but  the  mixture  is  ignited  as  it 
enters,  a  grating  arrangement  preventing  the  flame  from  passing 
back;  the  mixture,  in  fact,  does  not  enter  the  motor  cylinder  at  all ; 
what  enters  it,  is  a  continuous  flame.  At  a  certain  point  the  supply 
of  flame  is  cut  off  and  the  piston,  moving  on  to  the  end  of  its  stroke, 
expands  the  volume,  of  hot  gases  to  nearly  atmospheric  pressure 
before  discharge. 


Gas  Engines  of  Different  Types  in  Practice         1^3 

Fig.  40  is  an  external  view  of  the  engine.  Figs.  41  and  42  are 
sections  of  the  motor  and  pump  cylinders.  The  action  is  as  fol- 
lows : — The  engine  is  single  acting,  receiving  one  impulse  for  every 
revolution  ;  like  all  gas  engines  it  depends  upon  the  energy  stored 
up  in  the  fly  wheel  to  carry  it  through  those  parts  of  its  cycle 


FIG.  40.  —  Bray  ton  Petroleum  Engine. 

where  the  work  is  negative.  The  two  cylinders  are  inverted  and 
are  attached  to  a  beam  rocking  beneath  them,  by  connecting  rods. 
The  beam  is  prolonged  and  connected  to  the  crank  above  it  by  a 
rod  ;  both  cylinders  are  single-acting  and  the  pistons  are  of  the 
trunk  kind.  Both  pump  and  motor  cylinders  are  of  the  same 


j  5 4  Th*  &as  Engine 

diameter,  but  the  pump  is  only  half  the  stroke  of  the  motor.  The 
valves  are  actuated  from  a  shaft  running  at  the  same  rate  as  the 
main  shaft  and  driven  from  it  by  bevel  wheels.  There  are  four 
valves,  all  of  the  conical  seated  kind— two  upon  the  motor, 
admission  and  discharge,  two  upon  the  pump  cylinder,  admission 
and  discharge.  The  admission  and  discharge  valves  upon  the 
motor  are  actuated  from  the  auxiliary  shaft  by  levers  and  cams,  so 
is  the  pump  inlet.  The  pump  discharge  valve  is  automatic,  rising 
at  the  proper  time  by  the  pressure  of  compression.  During  the 
down-stroke  the  pump  takes  in  the  charge  of  gas  and  air,  forcing 
it  on  the  up-stroke  into  the  receiver.  From  the  receiver  it  is  led  to 
the  power  cylinder,  passing  by  the  inlet  valve  through  a  pair  of 
perforated  brass  plates  with  wire  gauze  placed  between,  them. 
Through  this  diaphragm  a  small  stream  of  mixture  is  constantly 
passing  into  the  motor  cylinder;  before  the  engine  is  started,  a 
plug  is  withdrawn  and  the  current  lighted  ;  a  constant  flame  is 
therefore  burning  under  the  diaphragm.  The  mixture  enters  the 
cylinder  through  this  flame,  lighting  as  it  enters  ;  at  all  times 
during  the  exhaust  part  of  the  stroke,  as  well  as  the  admission,  the 
stream  of  entering  mixture,  from  the  receiver,  keeps  up  a  small 
constant  flame  which  is  augmented  at  the  beginning  of  the  stroke, 
so  as  to  fill  the  cylinder  entirely,  when  the  admission  valve  is 
opened.  When  the  admission  valve  is  closed,  the  bye-pass  keeps 
the  flame  fed  with  sufficient  mixture  to  keep  it  alight.  The 
pressure  in  the  cylinder  thus  never  exceeds  that  in  the  reservoir 
and  the  mixture  burns  quietly  without  spreading  back. 

Figs.  40,  41  and  42.— A  is  the  motor  cylinder  ;  B  the  pump  ; 
the  beam  and  connections  require  no  lettering ;  c  is  the  pump 
inlet  valve  (the  pump  discharge,  which  is  an  ordinary  lift  valve,  is 
not  seen  in  fig.  42,  but  is  lettered  D  in  fig.  40)  ;  E  the  motor  inlet  ; 
F  the  igniting  plug  which  is  withdrawn  when  the  flame  is  to  be  lit 
before  starting  the  engine  (see  fig.  82) ;  G  is  the  grating  in  section 
(see  fig.  41);  H'  the  exhaust  valve;  the  levers  and  cams  are 
sufficiently  indicated  on  the  drawing  ;  the  small  pipe  and  stop- 
cock i  (fig.  40)  communicates  at  all  times  with  the  reservoir  and 
supplies  the  constant  flame  with  mixture.  The  engine  worked 
well  and  smoothly ;  the  action  of  the  flame  in  the  cylinder  could 
'not  be  distinguished  from  that  of  steam,  it.  was  as  much  within 


Gas  Engines -of  Different  Types  in  Practice         155 

control  and  produced  diagrams  quite  similar  to  steam.  The  flame 
grating  was  the  weak  point ;  it  stood  exceedingly  well  for  a  time,  but 
if  by  any  accident  the  gauze  was  pierced  in  cleaning,  the  flame 
went  back  into  the  reservoir  and  exploded  all  the  mixture — the 
engine,  of  course,  pulled  up  as  the  constant  flame  having  no  supply 


FIG.  41.  — Brayton  Engine. 
Section  of  Motor  Cylinder. 


FIG.  42. — Brayton  Engine. 
Section  of  Pump  Cylinder. 


was  extinguished.  This  accident  became  so  troublesome  that 
Mr.  Brayton  discontinued  the  use  of  gas  and  converted  his  engine 
into  a  petroleum  engine.  The  light  petroleum  was  pumped  upon 
the  grating  into  a  groove,  filled  with  felt,  the  compressing  pump 


156 


The  Gas  Engine 


then  charged  the  reservoir  with  air  alone.  The  air  in  passing 
through  the  grating  carried  with  it  the  petroleum,  partly  in  vapour, 
part  in  spray;  the  constant  flame  was  fed  by  a  small  stream  of  air. 
The  arrangements  were,  in  fact,  precisely  similar  to  the  gas  engine, 
except  in  the  addition  of  the  small  pump  and  the  slight  alteration 
in  the  valve  arrangements.  The  difficulty  of  explosion  into  the 
reservoir  was  thus  overcome,  but  a  new  difficulty  arose — the 
cylinder  accumulates  soot  with  great  rapidity  and  the  piston 
requires  far  too  frequent  removal  for 
cleaning.  The  petroleum  pump  is  an 
exceedingly  clever  little  contrivance  ; 
fig.  43  shows  its  details.  The  amount 
of  petroleum  to  be  injected  at  each 
stroke  is  so  small  that  an  ordinary  force 
pump  with  clack  valves  would  be  un- 
certain. Brayton  gets  over  this  difficulty 
by  substituting  a  slide  valve  driven  from 
the  eccentric. 

The  plunger  of  the  pump  is  no  larger 
than  a  black-lead  pencil,  yet  it  dis- 
charges any  quantity,  from  a  single  drop 
per  stroke  up  to  full  throw,  with-  un- 
erring certainty.  The  plunger  also  is 
driven  from  an  eccentric.  Both  eccen- 
trics are  in  one  piece  and  rotate  on  the 
end  of  the  auxiliary  shaft,  driven  by  a 
pawl  when  the  engine  is  in  motion  ;  to 
allow  of  starting,  the  pump  can  be 
moved  by  a  hand-crank  independently. 
To  start,  the  air  reservoir  is  filled,  if  not 
already  full,  by  turning  the  engine  round 
by  hand  ;  the  plug  F  is  then  withdrawn 
and  a  little  petroleum  thrown  upon  the  diaphragm  by  a  few  turns 
of  the  pump.  The  cock  i  on  the  small  pipe  is  then  opened  and 
a  stream  of  air  flowing  from  the  reservoir  vaporises  the  petroleum  ; 
H  is  lit  at  G,  and  the  flame  having  enough  air  for  combustion  retreats 
to  the  grating  and  remains  burning  within  the  cylinder.  The  plug 
is  then  inserted,  the  starting  cock  opened,  and  the  engine  starts. 


FIG.  43. 
Brayton  Petroleum  Pump. 


Gas  Engines  of  Different  Types  in  Practice         157 

The  flame  remains  alight  during  the  whole  time  the  petroleum 
continues  .to  be  supplied. 

The  valves  act  well  and  the  motor  cylinder  does  not  suffer 
from  the  action  of  the  flame  so  long  as  it  is  kept  reasonably 
clean.  If  the  soot,  however,  is  allowed  to  accumulate,  it  speedily 
cuts  up. 

Diagrams  and  Gas  or  Petroleum  Consumption. — Prof.  Thurston 
of  the  Stevens  Institute  of  Technology  tested  a  Brayton  gas  engine 
in  New  York  in  the  year  1873. 

The  following  extracts  are  from  his  report  : 

'  The  operation  of  the  engine  is  precisely  similar  in  the  action 
of  tfre  engine  proper  and  in  the  distribution  of  pressure  in  its 
cylinder,  to  that  of  the  steam  engine .  The  action  of  the  impelling 
fluid  is  not  explosive  as  it  is  in  every  other  form  of  gas  engine  of 
which  I  have  knowledge. 

'Upon  the  opening  of  the  induction  valve, 'the  mixed  gases 
enter,  steadily  burning  as  they  flow  into  the  cylinder,  and  the 
pressure  from  the  commencement  of  the  stroke  to  the  point  of  cut 
off,  as  is  shown  by  the  indicator  diagrams,  is  as  uniform  as  that 
observed  in  any  steam  engine  cylinder.  The  maximum  pressure 
exerted  during  my  experimental  trial,  and  while  the  engine  was 
driving  somewhat  more  than  its  full  rated  power,  was  about  75  Ibs. 
per  square  inch  at  the  beginning  of  the  stroke,  gradually  dimin- 
ishing to  66  Ibs.  per  square  inch  at  the  point  of  cut-off,  where 
the  speed  of  the  piston  was  nearly  at  a  maximum,  and  then  de- 
clining in  accordance  with  the  law  governing  the  expansion  of 
gases. 

'  Complete  combustion  is  insured  by  thorough  mixture.  This 
is  accomplished  by  taking  the  illuminating  gas  and  air,  in  proper 
proportion,  into  the  compressing  pump  together,  and  the  mixture 
here  made  becomes  more  intimate  in  the  reservoir,  and  in  its  pro- 
gress towards  the  point  at  which  it  does  its  work.  The  constantly 
burning  jet  already  described  insures  prompt  ignition  on  entering 
the  cylinder. 

'.  .  .  the  engine  rated  at  5  HP  developed,  as  a  maximum, 
rather  more  than  its  rated  power.  Its  mean  power  during  the  test, 
as  determined  by  the  dynamometer,  was  3*986  HP,  the  indicator 
showing  at  that  time  8-62  HP  developed  in  the  cylinder.  The 


i;3  The  Gas  Engine 

amount  of  gas  consumed  averaged  32-06  cubic  feet  per  indicated 
HP  per  hour. 

'The  excess  of  indicated  over  dynamometric  HP  is  to  be 
attributed  to  the  work  of  driving  the  compressing  pump  and  to  the 
friction  of  the  machine. 

'The  greater  portion  of  this  appears  both  in  debit  and  credit 
side  of  the  account,  since,  although  expended  in  the  compressing 
pump,  it  is  restored  again  in  the  driving  cylinder.' 

The  consumption  of  32-06  cubic  feet  per  horse  hour  is  incor- 
rect ;  it  is  obviously  unfair  to  include  the  pump  diagram  in  the 
gross  power.  The  author  has  tested  an  engine  of  similar  con- 
struction and  dimensions  ;  he  finds  the  friction  of  the  mechanism 


Max.  press.  68  Ibs.  per  sq.  in. 
FIG.  44. 


FIG.  45.  —  Diagrams  from  Brayton's  Gas  Engine. 

to  be  about  i -horse  ;  adding  this  number  to  the  dynamometric 
power  of  Prof.  Thurston,  the  legitimate  indicated  power  may  be 

taken  as  5  HP,  the  consumption  is  therefore  -  -  =55 '2; 

and  the  gas  per  brake  HP  per  hour  is  §^2Xj£o6  =  ^  These 

3-986 

numbers,  although  showing  improvement  upon  the  Lenoir  and 
Hugon,  prove  that  the  engine  was  much  inferior  in  economy  to 
the  Otto  and  Langen  engines. 

Mr.  H.  McMutrie,  Consulting  Engineer  at  Boston,  took  dia- 
grams from  an  engine  of  similar  dimensions  which  confirm  these 
results.  Fig.  44  is  the  diagram  taken  with  full  load,  fig.  45  the 
diagram  from  the  motor  with  no  load  on,  the  power  being  just 
sufficient  to  overcome  friction  and  pump  losses. 


Gas  Engines  of  Different  Types  in  Practice 


FULL  LOAD  DIAGRAM. 

Area  of  piston 50-26  sq.  ins. 

Speed  of  phton 180  ft.  per  min. 

Mean  pressure     .         .         .         .         .         .         -33  Ibs.  per  sq.  in. 

Pressure  in  reservoir 75 '4  Ibs.  per  sq.  in. 

Initial  pressure  in  cylinder 68  Ibs.  per  sq.  in. 

Gross  power  developed 9  HP. 

No  LOAD  DIAGRAM. 

Speed  of  piston 180  ft.  per  min. 

Mean  pressure 18  Ibs.  per  sq.  in. 

Friction  and  other  resistance        ....  4^87  HP. 

Net  available  power 9  —  4*87  =  4-13 

This  power  agrees  closely  with  the  actual  determination  by 
dynamometer. 

The  author  has  made  a  careful  trial  of  a  Brayton  petroleum 
engine  rated  at  5 -horse,  The  engine  was  made  by  the  '  New  York 
and  New  Jersey  Ready  Motor  Company  • '  it  was  sent  to  Glasgow 
and  the  following  test  was  made  at  the  Crown  Ironworks  on  the 
aist  and  22nd  February,  1878.  The  motor  cylinder  is  8  inches 
in  diameter  and  the  stroke  12  inches  ;  the  pump  cylinder  is  also 
8  inches  diameter  but  the  stroke  is  6  inches. 

Diagrams  were  taken  from  both  pump  and  motor  by  a  well- 
made  Richards'  indicator.  At  the  same  time  the  dynamometer 
was  applied  to  the  fly  wheel  fully  loading  the  engine,  readings  were 
taken  at  regular  intervals.  The  revolutions  were  recorded  by  a 
counter.  The  petroleum  used  was  measured  in  a  graduated  glass 
vessel . 

The  results  are  as  follows  : 

TEST  OF  BRAYTON  PETROLEUM  ENGINE.    (Clerk.} 

Petroleum  consumed  during  one  hour      .         .         .  1-378  gallons. 

Mean  speed  of  engine      ......  201  revs,  per  min. 

Mean  dynamometer  reading 4'26  HP. 

Mean  pressure,  power  cylinder          .         .         .  31  Ibs.  per  sq.  in. 

Mean  pressure,  air  pump          .....  27-6  Ibs.  per  sq.  in. 

Piston  speed,  motor         .-'..,         .         .         .    '    .  201  ft.  per  min. 

Piston  speed,  purrp ioo-s  ft.  per  itiin. 

Power  indicated  in  motor 9-49  HP. 

Power  indicated  in  pump 4'10  HP. 

Available  indicated  power        .  5 '39 


i6o 


The  Gas  Engine 


The  power  by  the  dynamometer  is  4'26-horse  ;  therefore  the 
mechanical  friction  of  the  engine  is  5-39— 4-26=1-13  horse. 


Consumption  of  petroleum 
Consumption  of  petroleum 


°'25S  galls,  per  IHP  per  hv. 
0-323  galls,  per  actual  HP  per  hr. 


Figs.  46  and  47  are  diagrams  from  the  motor  and  pump,  which 
are  fair  samples  of  those  taken.  It  will  be  observed  that  consider- 
able throttling  occurs  in  entering  the  motor  cylinder ;  the  pump 
pressure  is  higher  than  the  reservoir  pressure,  and  the  motor  pres- 
sure is  lower,  so  that  a  double  loss  has  been  incurred.  The  prin- 
ciple of  the  engine  is  so  good  that  the  author  anticipated  better 
results.  Great  improvement  could  be  obtained  by  reproportioning 


4-5 


Mean  pressure  30*2  Ibs.  per  sq.  in.     8  ins.  dia.  cylinder.     Stroke  12  ins.     200  revs,  per  min. 
FIG.  46. — Bray  ton  Petroleum  Engine.     Motor  Cylinder. 


Mean  pressure  27*6  Ibs.  per  sq,  in.     8  ins.  dia.  cylinder.     Stroke  6  ins.     200  revs,  per  min. 
FIG.  47.— Brayton  Petroleum  Engine.     Pump  Cylinder. 

the  valves  and  air  passages  ;  they  are  in  this  engine  much  too  small 
and  cause  needless  resistance  and  loss.  The  maximum  pressure 
in  the  motor  cylinder  is  48  Ibs.  per  square  inch,  which  remains 
steadily  till  the  inlet  valve  shuts  at  four-tenths  of  the  stroke  :  the 
pressure  then  slowly  falls  as  the  gases  expand,  the  exhaust  valve 
opening  at  about  ten  pounds  per  square  inch  above  atmosphere. 
The  average  available  pressure,  upon  this  diagram  is  30*2  Ibs. 


Gas  Engines  of  Different  Types  in  Practice         161 

per  square  inch.  The  air  pump  shows  a  maximum  pressure  of 
65  Ibs.  per  square  inch,  the  reservoir  pressure  being  60  Ibs.  The 
average  resistance  is  27-6  Ibs.  per  square  inch ;  as  the  pump  is  half 
the  stroke  of  the  motor  and  equal  to  it  in  area,  the  pressure  to  be 

deducted  is   2-^—   =  i^'S  and  30*2  —  13-8=  i6'4.     The  actual 

2 

available  pressure  actuating  the  engine  is  therefore  only  16*4  Ibs. 
per  square  inch.  The  effect  of  the  clearance  in  the  pump  cylinder 
is  noticeable  upon  the  diagram  ;  the  air  inlet  valve  does  not  open 
till  one-tenth  of  the  down  stroke  is  completed. 

The  theoretic  efficiency  of  this  type,  with  a  maximum  tempera- 
ture of  1600°  C,  compression  of  Co  Ibs.  per  square  inch  above 
atmosphere,  and  motor  cylinder  of  twice  the  pump  volume,  is  0-30  ; 
the  efficiency  of  the  gas  in  the  mixture  commonly  used,  i  volume  gas 
7  volumes  of  air,  is  0^40  (p.  113)  ;  so  that  if  the  conditions  of  loss 
by  cooling  are  no  worse  than  in  the  author's  explosion  experiments, 
and  the  diagram  appeared  perfect,  the  actual  indicated  efficiency 
would  be  o'3o  x  0-40  =  0*12.  That  is,  the  engine  should  convert 
1 2  per  cent,  of  the  heat  it  gets  as  gas  or  petroleum  into  indicated 
work.  But  the  diagram  is  imperfect  in  many  ways.  Using  the  mix- 
ture it  does,  the  diagram  should  show  a  maximum  temperature  of 
1600°  C.  at  least  ;  in  reality  the  highest  temperature  is  only  840°  C. 
The  flame  is  entering  the  cylinder  at  an  actual  temperature  of 
1600°  C.  during  the  whole  period  of  admission,  but  the  convec- 
tion has  so  greatly  increased  by  the  mixing  effect  of  the  entering 
current  that  greatly  increased  cooling  results  ;  accordingly,  when  the 
gases  are  fully  admitted  and  the  inlet  valve  is  closed,  the  gases  have 
only  a  temperature  of  840°  C.  instead  of  1600°  C.  After  admis- 
sion ceases,  the  expansion  line  from  45  Ibs.  to  lolbs.  pressure  is  far 
above  the  adiabatic,  indeed  it  is  isothermal,  the  combustion  is 
proceeding  and  the  small  igniting  flame  also  is  helping  to  sustain 
the  temperature. 

It  is  therefore  quite  evident  that  the  loss  of  heat  is  much  greater 
than  that  occurring  during  explosion  in  equal  time.  The  correction 
of  the  theoretic  efficiency  indicated  by  the  author's  closed  vessel 
experiments  is  insufficient,  o'i2  is  much  above  the  actual  effici- 
ency. Taking  the  heating  value  of  the  American  coal  gas  used 
in  Prof.  Thurston's  experiments  as  10,900  heat  units  per  unit  weight 

M 


1 62  The  Gas  Engine 

of  gas  burned,  and  one  pound  of  it  as  measuring  30  cubic  feet., 
then  as  the  engine  used  55  cubic  feet  per  IHP  per  hour,  its 
efficiency  is  0*071;  that  is,  it  converts  yi  per  cent,  of  the  heat  given 
to  it  into  work. 

This  is  a  poor  result  for  a  cycle  having  so  high  a  theoretic 
efficiency,  and  in  the  author's  experiments  with  petroleum  it  is 
even  worse. 

The  sp.  gravity  of  the  petroleum  was  0-85,  therefore  the  weight 
of  one  gallon  is  8-5  Ibs.  As  0*255  gallons  are  burned  per  indi- 
cated horse  power  per  hour,  this  amounts  to  8-5  x  0-255  =  2-16  Ibs. 
of  liquid  fuel  per  IHP  per  hour.  One  pound  gives  out  11,000 
heat  units,  and  for  one  horse  power  for  one  hour  1424  units  are 
required ;  the  actual  indicated  efficiency  is  therefore 

_  =  J424    _  O.o6  neariy  .  that  is,  6  per  cent,  of  the 
2'ioxuooo         23760 

whole  heat  given  to  the  engine  is  accounted  for  by  the  power 
developed  in  the  motor  cylinder. 

If  there  were  no  losses  of  heat  to  the  cylinder,  or  losses  by 
throttling  during  the  inlet  and  transfer  of  the  air  from  the  pump 
to  the  motor  or  loss  of  heat  from  the  reservoir  to  the  atmosphere, 
then  the  efficiency  of  this  type  of  engine  would  be  30  per  cent. 
These  losses  in  practice  reduce  it  to  6  per  cent.  The  cycle  is  a 
good  one,  and  under  other  circumstances  is  capable  of  better 
things,  but  it  is  quite  unsuitable  for  a  cold  cylinder  engine.  Cool- 
ing and  undue  resistance  are  the  main  causes  of  the  great  deficit. 

The  gases  entering  the  cylinder  as  flame,  in  passing  through 
the  inlet  chamber  expose  a  large  surface  to  the  action  of  the  water 
jacket ;  the  entering  currents  also  impinge  against  the  piston, 
causing  more  rapid  circulation  than  ordinary  convection.  Both 
causes  intensify  the  cooling  action  of  the  cylinder  walls.  In  the 
engine  tested  by  the  author  the  communicating  pipes  and  the 
motor  admission  valve  were  much  too  small  ;  a  considerable  loss 
of  pressure  resulted  ;  although  the  reservoir  pressure  was  60  Ibs., 
that  in  the  cylinder  never  exceeded  48  Ibs.  above  atmosphere, 
showing  a  loss  of  12  Ibs.  per  square  inch  from  undue  resistance. 
To  enable  this  engine  to  realise  the  advantages  of  its  theory  con- 
siderable modifications  in  its  arrangements  are  required.  Notwith- 
standing all  difficulties  it  has  done  much  useful  work,  not  the  least 


Gas  Engines  of  Different  lypes  in  Practice         163 

notable  being  the  assistance  it  rendered  to  Prof.  Draper  during  his 
investigation  on  the  existence  of  non-metallic  bodies  in  the  sun's 
atmosphere.  He  used  a  Brayton  petroleum  engine  for  driving  his 
dynamo  machine,  and  he  stated  in  his  paper  that  its  ease  of  starting 
and  almost  absolute  steadiness  in  driving  were  of  the  greatest  ser- 
vice to  him.  In  steadiness  he  states  that  '  it  acted  like  an  instru- 
ment of  precision.' 


FIG.  48. — Simon  Engine. 

Simon  Engine. — Messrs.  Simon,  of  Nottingham,  introduced  the 
Brayton  engine  to  England  in  a  slightly  altered  form  as  a  gas 
engine.  In  addition  to  the  ordinary  arrangements  of  the  engine 
they  attempted  to  gain  increased  economy,  by  causing  the  waste 
heat  passing  into  the  water  jacket,  and  the  heat  of  the  exhaust 

M  2 


1 64  The  Gas  Engine 

gases,  to  be  utilised  in  raising  steam.  They  would  undoubtedly 
have  increased  the  economy  of  the  engine  in  this  manner  had 
they  not  turned  the  steam  so  raised  into  the  motor  cylinder  along 
with  the  flame.  The  cooling  of  the  flame  which  was  serious 
enough  in  the  original  was  thus  made  worse,  and  but  slight  gain 
could  result,  the  loss  by  cooling  being  slightly  exceeded  by  the 
increase  of  volume  due  to  the  steam.  Fig.  48  is  an  external  view 
of  the  engine  as  exhibited  at  the  Paris  Exhibition  of  1878.  A  is 
the  motor,  B  the  pump,  and  c  the  added  boiler  ;  the  steam  was 
raised  in  it  and  the  water  jacket.  With  a  suitable  arrangement 
using  the  steam  in  a  separate  cylinder,  doubtless  6  per  cent,  might 


7  ins.  dia.  of  cylinder  ;  240  ft.  per  min.  piston  speed.     Scale  ^  in. 
FIG.  49. — Diagram  from  Simon  Engine. 

be  added- to  the  indicated  efficiency  of  the  engine,  but  it  is  very 
questionable  if  the  increased  complexity  does  not  entirely  destroy 
any  advantage  gained ;  it  certainly  does  so  in  small  engines.  When 
very  large  engines  come  to  be  constructed  the  complexity  would 
not  be  so  great  and  it  would  be  well  worth  while  to  use  waste  heat 
in  steam  raising.  The  engine,  although  instructive,  did  not  suc- 
cessfully overcome  the  difficulties  which  caused  .the  abandonment 
of  the  Brayton  as  a  gas  engine.  Fig.  49  is  a  diagram  from  the 
engine  which  forcibly  illustrates  the  effect  of  the  cooling. 


Gas  Engines  of  Different  Types  in  Practice         165 


TYPE  III. 

Engines  of  this  kind  resemble  those  just  discussed,  in  the  use 
of  compression  previous  to  ignition,  but  differ  from  them  in  ignit- 
ing at  constant  volume  instead  of  constant  pressure  ;  that  is,  the 
whole  volume  of  mixture  used  for  one  stroke  is  ignited  in  a  mass 
instead  of  in  successive  portions. 

The  whole  body  of  mixture  to  be  used  is  introduced  before 
any  portion  of  it  is  ignited  ;  in  the  previous  type  the  mixture  is 
ignited  as  it  enters  the  cylinder,  no  mixture  being  allowed  to  enter 
except  as  flame.  In  Type  III  the  ignition  occurs  while  the  volume 
is  constant  ;  the  pressure  therefore  rises  ;  it  is  an  explosion  engine 
in  fact,  like  the  first  type,  but  with  a  more  intense  explosion  due 
to  the  use  of  mixture  at  a  pressure  exceeding  atmosphere. 

The  most  obvious  means  of  applying  the  method  is  that  sug- 
gested by  the  Lenoir  engine.  The  addition  of  a  pump  taking 
mixture  at  atmospheric  pressure,  compressing  it  into  a  reservoir 
from  which  it  passes  to  the  motor  cylinder  at  the  increased  pres- 
sure, seems  a  simple  matter.  The  igniting  arrangements  would 
act  as  in  the  original.  As  the  gases  are  under  pressure,  the  piston 
would  take  its  charge  into  the  cylinder  in  a  smaller  proportion  of 
the  forward  stroke,  and  so  more  of  the  motor  stroke  would  be 
available  for  useful  effect.  The  diagram  such  an  engine  should 
produce  is  seen  at  fig.  15,  p.  50;  the  shaded  part  is  the  available 
portion,  the  other  part  is  the  pump  diagram.  The  theoretic  effi- 
ciency of  such  an  engine  is  as  good  as  the  type  can  give.  The 
patent  list  shows  that  it  was  the  first  proposed  after  Lenoir.  Many 
such  engines  have  been  attempted  and  have  given  very  good  re- 
sults economically,  but  the  difficulties  of  detail  are  considerable, 
the  greatest  being  the  necessity  for  the  intermediate  reservoir. 
Million's  patent  1861  proposes  to  do  this,  the  present  author  also 
constructed  one  of  this  kind  in  1878,  and  later  one  was  made  by 
Mr.  Atkinson.  The  difficulties,  however,  are  too  great  to  allow  the 
success  of  small  motors  on  the  plan. 

Mr.  Otto,  the  first  to  succeed  with  the  free  piston  engine,  was 
also  the  first  to  succeed  in  adapting  compression  in  a  reliable 
form. 


The  Gas  Engine 

In  the  third  type  are  included  all  engines  having  the  following 
characteristics,  however  widely  the  mechanical  cycle  may  vary  : 

Engines  using  a  gaseous  explosive  mixture,  compressed  before 
ignition,  and  ignited  in  a  body,  so  that  the  pressure  increases  while 
the  volume  remains  constant.  The  power  is  obtained  by  expan- 
sion after  the  increase  of  pressure. 

Otto  Engine.— In  this  gas  engine,  the  first  to  combine  the 
compression  principle  with  a  simple  and  thoroughly  efficient  work- 
ing cycle,  the  difficulties  of  compression  are  overcome  in  a  strikingly 
original  manner.  To  the  engineer  accustomed  to  the  steam 
engine,  the  main  idea  seems  a  bold  and  indeed  a  retrograde  step. 
The  early  gas  engines  were  moulded  more  upon  the  steam  engine 
model  and  were  to  some  extent  double  acting.  The  Lenoir  and 
Hugon  both  received  two  impulses  for  every  revolution,  the 
Brayton  was  single  acting,  and  the  Otto  is  only  half  single  acting. 
The  steam  engine  in  its  advance  passed  from  single  to  double 
acting,  and  then  to  four  and  even  more  impulses  per  revolution. 
The  gas  engine  in  its  progress  has  in  this  respect  moved  backwards, 
beginning  with  double  action  and  then  going  back.  The  gain  of 
this  arrangement,  however,  has  completely  justified  the  retro- 
gression. 

In  external  appearance  the  engine  closely  resembles  a  modern 
high  pressure  steam  engine,  the  working  parts  of  which  are  of 
somewhat  excessive  strength  ;  its  motor  and  only  cylinder  is  hori- 
zontal and  open  ended  ;  in  it  works  a  long  trunk  piston,  the  front 
end  of  which  serves  as  a  guide  and  does  not  enter  the  cylinder 
proper  ;  the  connecting  rod  communicates  between  the  guide  and 
the  crank  shaft,  the  side  thrust  is  thus  kept  off  the  piston  and 
cylinder  proper,  which  become  hot.  The  crank  shaft  is  heavy  and 
the  fly-wheel  a  large  one  ;  considerable  energy  being  required  to 
take  the  piston  through  the  negative  part  of  the  cycle.  The 
cylinder  is  considerably  longer  than  the  piston  stroke,  so  that  the 
piston  when  full  in  leaves  a  considerable  space  into  which  it  does 
not  enter. 

Outside  the  cylinder,  running  across  it  at  the  end  of  the  space, 
works  a  large  slide  valve  ;  it  is  held  against  the  cylinder  face  by 
a  cover  plate  and  strong  spiral  springs  ;  it  is  driven  to  and  fro  by 
a  small  crank,  on  the  end  of  a  shaft  parallel  to  the  cylinder  axis, 


Gas  Engines  of  Different  Types  in  Practice         167 


The  Gas  Engine 

and  rotating  at  half  the  rate  of  the  crank  shaft,  from  which  it 
receives  its  motion  by  bevel  or  skew  gearing. 

An  exhaust  valve,  leading  into  the  space  by  a  port,  is  also 
actuated  at  suitable  times  from  the  secondary  shaft ;  so  are  the 
governing  and  oiling  gear. 

The  single  cylinder  serves  alternately  the  purposes  of  motor 
and  pump  ;  during  the  first  forward  stroke  of  the  piston,  the  slide 
valve  is  in  such  position  that  gas  and  air  stream  into  the  cylinder 
from  the  beginning  to  the  end  of  the  stroke,  the  charge  mixing  as 
it  enters  with  whatever  gases  the  space  may  contain  ;  the  return 
stroke  then  compresses  the  uniform  mixture  into  the  space,  and 
when  the  piston  is  full  in,  the  pressure  has  increased  to  an  amount 
determined  by  the  relative  capacity  of  the  space.  Meantime  the 
slide  valve  has  moved  to  another  position,  first  closing  the  admission 
gas  and  air  ports,  to  permit  of  the  compression,  then  bringing  on  a 
cavity  in  the  valve  which  is  filled  with  flame,  when  the  compression 
is  completed.  The  compressed  charge  therefore  ignites  and  the 
pressure  rises  so  rapidly  that  maximum  is  attained  before  the  piston 
has  moved  appreciably  on  its  forward  stroke  (second  stroke)  ; 
the  piston  is  thus  under  the  highest  pressure  at  the  beginning  of 
its  stroke  and  the  whole  stroke  is  available  for  the  expansion. 

This  is  the  motive  stroke.  At  the  end  of  it,  the  exhaust  valve 
opens  and  the  return  stroke  is  occupied  in  driving  out  the  burned 
gases,  except  that  portion  remaining  in  the  space  which  cannot  be 
entered  by  the  piston.  These  operations  form  a  complete  cycle, 
and  the  piston  is  again  in  the  position  to  take  in  the  charge  re- 
quired for  the  next  impulse. 

The  cycle  requires  two  complete  revolutions,  or  four  single 
strokes. 

First  out  stroke.  Charging  cylinder  with  gas  and  air. 

>,     in        „  Compressing  the  charge  into  the  space. 

Second  out  stroke.  Explosion  impelling  piston. 

»         in        „  Discharging  burned  gases  into  atmosphere. 

The  regulation  of  the  speed  of  the  engine  is  accompli'shed  by 
a  centrifugal  governor,  which  is  arranged  to  close  a  gas  supply 
valve  whenever  the  speed  increases,  An  explosion  is  thereby 
missed,  and  the  engine  goes  through  its  cycle  as  usual,  but  as  no 


Gas  Engines  of  Different  Types  hi  Practice         169 


The  Gas  Engine 

gas  is  mixed  with  the  air,  there  is  no  explosion  when  the  flame 
enters,  the  compressed  air  merely  expanding,  giving  back  to  the 
piston  the  energy  taken  during  compression. 

When  running  without  load,  8  or  even  more  revolutions  maybe 
made  between  the  impulses,  at  full  load  2  revolutions  are  made  per 
impulse.  Notwithstanding  this  irregularity  the  fly-wheel  is  so 
large  that  no  variation  observable  by  the  eye  can  be  seen  while 
watching  the  engine. 

Fig.  50  is  an  external  elevation  of  an  Otto  engine. 

Fig.  51  is  a  sectional  plan,  and  fig.  52  an  end  elevation  showing 
exhaust  valve  lever.  A  is  the  water-jacketed  cylinder,  B  the  piston 
shown  full  in,  c  is  the  compression  space  or  cartridge  space  as  it 
is  called  by  Million;  i  the  admission  and  ignition  port,  communi- 
cating alternately  with  the  gas  and  air  admission  port  K,  and  the 
flame  port  L  in  the  slide  M  ;  N  is  the  cover  holding  the  slide  to  the 
cylinder  face  and  carrying  in  it  the  external  flame  for  lighting  :he 
movable  one  in  flame  port  L.  The  exhaust  valve  is  of  the  conic;  1 
seated  lift  type  and  is  seen  at  o;  it  is  driven  from  the  shaft  P  by 
the  cam  Q  and  the  lever  R.  The  other  details  are  clearly  shown 
upon  the  drawing.  The  ignition  valve  and  governing  arrangement 
will  be  described  in  a  subsequent  chapter  ;  here  it  is  sufficient 
to  state  that  the  governor  withdraws  a  cam  actuating  the  gas 
valve  s,  fig.  52,  and  so  prevents  it  opening  when  the  piston  is 
taking  in  air.  When  open,  the  gas  passes  the  valve,  then  through 
a  row  of  holes  in  the  valve  port  K,  streaming  into  the  air  and  mix- 
ing thoroughly  with  it  as  it  enters  the  cylinder.  To  start  the 
engine,  the  flame  at  T  is  lighted  ;  the  cock  commanding  the  internal 
flame  being  properly  adjusted,  and  the  gas  turned  on,  a  couple  of 
turns  at  the  fly-wheel  should  cause  ignition  and  set  the  engine 
in  motion.  The  larger  engines  are  provided  with  a  second  cam, 
which  keeps  the  exhaust  valve  open  during  half  of  the  compression 
stroke  and  so  diminishes  the  work  required  to  turn  round  the  engine 
by  hand.  When  the  engine  is  started  the  wheel  upon  the  lever  is 
shifted  to  the  normal  cam  and  the  compression  then  returns  to  its 
usual  intensity. 

Diagrams  and  Gas  Consumption. — Dr.  Slaby,  of  Berlin,  has 
made  a  very  careful  trial  of  a  four-horse  power  Otto  engine  at 
Mr.  Otto's  works;  Deutz,  in  August  1881. 


Gas  Engines  of  Different  Types  in  Practice         171 


FIG.  52. -Otto  Engine  (End  elevation). 


Ij2  The  Gas  Engine 

The  dimensions  of  the  engine  are  : 

Diameter  of  cylinder 171-9  millimetres. 

Stroke •  34°  millimetres. 

Compression  space 477°  cb.  centimetres. 

Volume  displaced  by  piston      ....  7888  cb.  centimetres. 

The  compression  space  is  therefore  0*6  of  the  volume  displaced  by 
the  piston.  The  results  are  briefly  as  follows : 

Average  revolutions  during  t^st         .         .         .  1567  per  minute. 

Power  indicated  in  cylinder      ....  5-04  horse. 

Power  by  dynamometer    .....  4*4  horse. 

Gas  consumed  in  one  hour       ....  142-67  cb.  ft. 

Gas  con-um^cl  in  one  hour  by  igniting  flames  .  275  cb.  ft. 

Gas  consumption  per  1HP  per  hour         .         .  28-3  cb.  ft. 

Gas  consumption  per  effective  HP  hour  .         .  32'4  c'°-  ft- 

The  composition  of  the  gas  used  at  the  Gasmotoren-Fabrik, 
Deutz,  is  given  as  — 

Volumes. 

Marsh  gas,  CH4 34 '4 

Ethylene,  CoH4 3'5 

Hydrogen,  H 56-9 

Carbonic  oxide,  CO 5'2 

lOO'O 

and  i  cubic  metre  of  it  weighs  0*404  kilograms.  One  pound 
weight  of  it  therefore  measures  39*6  cubic  feet.  Deducting  the 
latent  heat  of  steam  produced,  i  pound  weight  evolves  heat  enough 
to.  raise  12,094  Ibs.  of  water,  through  one  degree  Centigrade.  It 
evolves  1 2, 094  heat  units.  From  this  value,  and  the  experimental 
determination  of  the  heat  leaving  the  engine  by  way  of  the  water 
jacket,  Dr.  Slaby  calculates  the  disposition  of  100  heat  units  given 
to  the  engine  as  follows  : 

Work  indicated  in  cylinder         .         .         .         .         .         ,         .     i6'o 

Heat  lost  to  cylinder  walls 51*0 

H-at  carried  away  by  exhaust 31  "o 

Heat  lost  from  engine  by  conduction  and  radiation  .         .         .2-0 

100 'O 

The  actual  indicated  efficiency  of  the  engine  is  therefore  16 
per  ^ent.  or  o'i6. 

The  temperature  of  the  gases  expelled  during  the  exhaust 
stroke  was  determined  by  carefully  protecting  the  exhaust  pipe 


Gas  Engines  of  Different  Types  in  Practice         173 

from  loss  of  heat  by  non-conducting  material,  and  then  seeing 
whether  zinc,  or  antimony  would  melt  in  it.  Zinc  melted  but 
antimony  did  not;  as  the  melting  point  of  zinc  is  423°  C,  and  the 
antimony  melting  point  is  432°  C.,  the  temperature  of  the  exhaust 
gases  is  given  with  great  accuracy  as  between  these  two  tempera- 
tures. The  average  composition  of  the  mixture  is  given  as  i  vol. 
coal  gas  to  1373  vols.  of  air  and  other  gases.  Here  Dr.  Slaby  is 
plainly  in  error,  as  his  own  figures  conclusively  show.  The  volume 
of  coal  gas  taken  into  the  engine  at  each  stroke  as  measured 
by  the  gas  meter  is  given  as  859  cubic  centimetres,  the  total 
volume  swept  by  the  piston  of  the  engine  per  stroke  is  7888  cubic 
centimetres,  the  volume  of  the  compression  space  4770  cubic 
centimetres.  Now  if  the  gas  be  introduced  into  the  cylinder 
while  it  is  filled  completely,  space  included,  with  cold  gases,  at 
the  same  temperature  as  the  gases  when  measured  by  the  meter, 
this  figure  is  correct  enough.  But  the  gases  are  not  so  introduced, 
the  space  is  already  filled. with  exhaust  gases  at  a  temperature  of 
about  400°  C.  by  Dr.  Slaby's  own  determination  ;  this  volume 
must  therefore  be  calculated  to  atmospheric  temperature  before 
an  approach  to  the  true  ratio  can  be  obtained.  Taking  atmo- 
spheric temperature  at  17°  C.,  then  4770  cubic  centimetres  of 
burned  gases  at  400°  C.  becomes  reduced  to  2055  cubic  centi- 
metres at  17°  C. ;  that  is,  the  total  charge  will  consist  of  859  cubic 
centimetres  of  coal  gas,  7029  cubic  centimetres  of  air,  and  2055 
cubic  centimetres  of  burned  gases  from  the  previous  explosion. 
The  ratio  is 

coal  gas  859  i 

air  and  burned  gases      7029  4-  2055        10-5 

The  composition  of  the  charge  is  more  correctly  represented 
as  i  vol.  of  gas  to  10-5  vols.  of  air  and  other  gases.  Even  here, 
however,  the  dilution  is  overstated,  as  it  is  assumed  that  the 
piston  has  taken  in  the  charge  at  full  atmospheric  temperature 
and  pressure.  But  there  is  some  throttling  in  passing  through  the 
admission  valve  and  port,  and  also  some  heating  of  the  air  by 
striking  the  piston  and  cylinder  walls.  Professor  Thurston,  in 
experiments  to  be  described  later  on,  proves  this  to  be  the  case, 
and  shows  that  the  charge  is  even  stronger  than  has  been 
calculated. 


1 74  The  Gas  Engine 

It  has  been  already  proved  that  in  this  type  of  engine,  ex- 
panding after  compression  and  explosion  to  the  same  volume  as 
existed  before  compression,  the  theoretic  efficiency  is  independent 
of  the  temperature  of  the  explosion  or  the  temperature  existing 
before  compression,  and  depends  only  upon  the  volume  before  and 
after  complete  compression.  As  the  ratio  of  compression  space 
to  volume  swept  by  the  piston  is  o-6  to  i,  the  volume  before 
compression  is  i-6,  volume  after  compression  o-6. 

The  theoretic  efficiency  is  (p.  53)  E  =  i  —  (-' 


and  rc  is  the  compression  volume,  and  ra  the  volume  before  com- 

/o-6\  '4o8  /    i    \  '4°8; 

pression  ;  in  this  case  E  =  I  —  (  -—        or  i  — 

\i  6/  \2-66j 

here  E  =  0-33. 

That  is,  if  all  the  heat  were  given  to  the  engine  at  the  moment 
of  complete  explosion  at  the  beginning  of  the  stroke,  and  no  heat 
were  lost  to  the  cylinder  during  the  expansion  to  the  original 
volume,  then  33  per  cent,  of  that  heat  would  be  converted  into 
indicated  work.  But  the  author's  explosion  experiments  give  the 
factor  necessary  for  correcting  this  theoretical  number  (p.  113). 
Taking  the  mixture  of  i  gas  to  10  vo!s.  air  as  nearest,  the 
efficiency  of  the  gas  in  it  is  0-46 ;  that  is,  during  the  time  of  the 
forward  stroke,  taken  as  0*2  sec.,  i  vol.  of  gas  is  required  to  pro- 
duce and  keep  up  a  pressure  which  0-46  vol.  would  suffice  for  if 
it  was  all  applied  to  heating  and  no  loss  by  cooling. 

The  actual  indicated  efficiency  of  the  engine  using  this 
mixture  and  this  expansion  and  compression  should  be  0*33  x 
0-46=0-152  nearly.  That  is,  the  engine  should  convert  15*2  per 
cent,  of  the  heat  given  to  it  into  work.  Dr.  Slaby's  number,  found 
by  experiment,  is  16  per  cent.  The  numbers  are  exceedingly 
close. 

The  mechanical  efficiency  of  the  engine  is  high,  the  ratio  of 
dynamemetric  to  indicated  power  being  8  7  to  100,  and  the  friction 
of  the  engine  only  0-64  horse 


Gas  Engines  of  Different  Types  in  Practice         175 


PROFESSOR  THURSTON'S  EXPERIMENTS  ON  A  6  HP  OTTO 
ENGINE. 

Dr.  Slaby's  experiments  are  exceedingly  complete,  but  Pro- 
fessor Thurston  in  America  has  made  even  more  extended 
measurements. 

Messrs.  Brooks  and  Steward  made  the  trials  under  the  direc- 
tion of  Professor  Thurston,  at  the  Stevens  Institute  of  Technology, 
Hoboken.  The  dimensions  of  the  engine  are  as  follows  : 

Diameter  of  cylinder 8-5  ins. 

Stroke 14  ins. 

Capacity  of  compression  space  38  per  cent,  of  total  cylinder 
volume. 

Not  only  was  the  gas  entering  the  engine  measured,  but  at  the 
same  time  the  ajr  required  was  measured  through  a  300  light 
meter.  So  far  as  the  author  is  aware,  this  is  the  only  set  of 
experiments  in  which  this  was  done  ;  it  is  by  far  the  most  accurate 
way  of  getting  the  true  proportions  of  the  explosive  mixture. 

The  temperature  of  the  exhaust  was  measured  by  a  pyrometer, 
and  the  power  determined,  both  by  indicator  and  dynamometer  ; 
at  the  same  time  the  heat  passing  into  the  walls  of  the  cylinder 
was  determined  by  measuring  the  water  heated  and  estimating 
the  loss  by  radiation  and  conduction. 

The  total  number  of  revolutions  during  the  various  tests  were 
taken  by  a  counter.  Many  trials  were  made  under  varying  con- 
ditions of  load  and  mixture  used  The  following  is  the  best  full- 
power  trial,  giving  the  most  economical  results : 

Average  revolutions  during  test    .         ,        »  .  .  158  per  minute. 

Power  indicated  in  cylinder .         ,         .       . »  •  •         9 '6  horsa. 

Power  by  dynamometer         .         ...         .  .         8' i  horse. 

Gas  consumed  in  one  hour   .         .         .         .  -; ,  .  235  cb.  ft. 

Gas  consumption  per  I  HP  p-r  hour     .         .  .  .  24-5  cb.  ft. 

Gas  consumption  per  effective  HP  per  hour  ,  .  29'!  cb.  ft. 

An  analysis  of  the  gas  used  during  the  trials  made  by  Thomas 
B.  Stillman,  Ph.D.,  is  as  follows  : 


176  The  Gas  Engine 

Hydrogen,  H 39*5 

Marsh  gas,  CH4 37'3 

Nitrogen,  N 8 '2 

Heavy  hydrocarbon5,  CoH0,  &c 6 '6 

Carbonic  oxide,  CO 4'3 

Oxygen,  O ...  1-4 

Water  vapour  and  impurities  (H2O,  CO>,  H2S)   .         .         .27 

lOO'O 

One  cubic  metre  of  this  gas  weighs  o'6o6  kilograms.  One 
pound  weight  of  it  therefore  measures  26-43  cubic  feet.  One 
pound  when  completely  burned  evolves  heat  enough  to  raise  9070 
Ibs.  water  through  i°  C. 

The  air  necessary  to  supply  just  enough  oxygen  for  the 
complete  combustion  of  i^  vol.  of  this  gas  is  5-94  vols. 

From  these  values  and  experiments  upon  temperature  of  the 
exhaust  gases,  Professor  Thurston  estimates  the  disposition  of  100 
heat  units  by  the  engine  as  follows : 

Work  indicated  in  cylinder  .         .         .         .         .         .  17 -o 

Heat  lost  to  cylinder  walls    ...          ....  52-0 

Heat  carried  away  by  exhaust  gases      .....  i5'5 

Heat  lost  from  engine  by  conduction  and  radiation      .         .  i  =;  '5 


The  actual  indicated  efficiency  is  therefore  17  per  cent. 

The  number  showing  the  proportion  of  heat  passing  into  the 
water  jacket  is  also  very  nearly  Slaby's,  but  the  amount  expelled 
with  the  exhaust  is  much  understated.  The  amount  lost  by  radi- 
ation is  overstated. 

The  temperature  of  the  exhaust  gases,  as  determined  by  a 
pyrometer  placed  in  the  exhaust  pipe,  varies  in  the  experiments  at 
full  load  from  399°  C.  to  432°  C.,  thus  practically  coinciding  with 
Slaby.  The  ratio  of  air  to  gas  was  found,  by  actual  measurement 
of  both,  to  be  about  7  to  i  when  the  engine  was  working  most 
economically.  Although  with  better  gas  the  ratio  would  be 
slightly  increased,  yet  it  could  not  equal  that  usually  given  for  the 
Otto  engine,  10  to  i  or  thereabouts. 

The  ratio  is  commonly  obtained  from  a  measurement  of  the 
gas  consumption -alone,  the  air  being  reckoned  as  the  volume  of 
the  piston  displacement,  less  the  measured  amount  of  gas.  This 
is  not  an  accurate  method,  for  the  reason  already  stated. 


Gas  Engines  of  Different  Types  in  Practice.        1 77 

If  the  mixture  filling  the  cylinder  mingles  with  the  burned 
gases  filling  the  compression  space,  then  the  average  composition 
of  the  charge  is  i  voL  coal  gas  to  9'!  vols.  of  other  gases. 


The  Gas  Engine 

Fig.  53  is  a  fair  sample  of  the  diagrams  obtained  during  Pro- 
fessor Thurston's  tests  while  the  engine  was  giving  full  power. 
The  piston  while  moving  from  the  point  i  to  the  point  2  takes 
in  the  charge  ;  the  pressure  in  the  cylinder  falls  below  atmo- 
sohere  as  the  piston  approaches  the  end  of  its  stroke.  This  is 
due  to  the  resistance  of  the  valve  port  to  entering  air  and 
gas.  The  piston  returns  from  2  to  5  (ist  in-stroke)  compress- 
ing the  charge,  the  pressure  increasing  to  atmosphere  at  the 
point  3,  the  compression  being  complete  at  the  point  5  ;  the 
ignition  then  occurs,  and  the  pressure  and  temperature  rapidly 
rises  as  the  explosion  progresses ;  the  temperature  does  not 
attain  its  maximum  till  the  piston  has  moved  forward  a  little  and 
has  reached  the  point  6.  From  that  point  to  7,  when  the  ex- 
haust valve  opens,  the  expanding  line  is  as  nearly  as  possible 
adiabatic.  The  temperatures  are  marked  at  each  point  of  the 
diagram.  The  return  stroke  from  2  to  i  discharges  the  products 
of  combustion.  This  is  the  second  in-stroke,  completing  the 
cycle  and  leaving  the  engine  in  position  to  again  take  in  the 
charge. 

The  diagram  shows  the  whole  changes  occurring  during  two 
complete  revolutions  of  the  machine  while  fully  loaded.  Fig.  54 
shows  what  occurs  when  the  governor  acts,  when  the  engine  is  at 
less  than  full  load.  The  smaller  diagram,  B,  is  the  normal  one, 
and  the  larger,  A,  the  intermittent  one  ;  the  gas  has  been  com- 
pletely cut  off  for  several  strokes,  and  so  the  hot  burned  gases  in 
the  compression  space  have  been  completely  discharged  and  re- 
placed by  pure  air  at  a  temperature  not  far  removed  from  atmo- 
spheric ;  the  explosion  then  causes  a  higher  pressure  by  nearly  half 
an  atmosphere,  although  the  maximum  temperature  is  less  than  in 
the  usual  case. 

The  temperature  of  the  charge  before  explosion  being  less,  a 
smaller  increase  is  required  to  produce  a  given  increase  of  pressure. 
Professor  Thurston  calculates  that  the  heat  accounted  for  by  the 
diagram  is  60  per  cent,  of  the  total  heat  supplied  to  the  engine ; 
the  deficiency  he  attributes  to  the  phenomena  of  dissociation, 
which  prevents  the  complete  evolution  of  the  heat  at  the  highest 
temperature,  but  permits  further  combustion  when  the  temperature 
falls.  The  amount  of  gas  required  to  run  at  full  speed,  166  revo- 


Gas  Engines  of  Different  Types  in  Practice         179 

lutions  per  minute  without  any  load,  was  found  to  be  from  50  to 
70  cubic  feet  per  hour. 


Other  tests  of  Otto  Engine.— The  experiments  of  Dr.  Slaby  and 
Vofessor  Thurston  upon  the  Otto  engine  are  by  far  the  most 
omplete  which  have  yet  been  made  to  the  author's  knowledge. 


i  So  The  Gas  Engine 

Some  tests  given  in  Schottler,  however,  will  be  quoted.  A  four 
HP  engine  was  found  to  consume  as  a  best  result  32-4  cubic 
feet  of  gas  per  brake  HP  per  hour  in  Altona,  giving  at  the  time 
3-96  HP  on  the  dynamometer.  Another  consumed  337  cubic 
feet  per  brake  HP  per  hour  in  Hanover,  giving  4-95  HP  on 
the  dynamometer;  to  drive  the  last  engine  at  160  revolutions  per 
minute  without  load  required  41-3  to  43-4  cubic  feet  of  Hanover 
gas. 

A  two-horse  engine,  tested  by  Erauer  and  Slaby,  Berlin,  gave 
2*28  brake  HP,  using  35*3  cubic  feet  per  brake  HP  per  hour. 

In  this  country  the  coal  gas  in  common  use  is  of  higher  heat- 
ing value  than  that  used  on  the  Continent  and  in  America ;  ac- 
cordingly the  gas  required  per  HP  is  less,  but  the  efficiency  is 
almost  identical. 

Experiments  made  upon  an  8  HP  Otto  engine  by  the  Philo- 
sophical Society  of  Glasgow  in  1880,  showed  a  consumption  of 
22  cubic  feet  of  Glasgow  gas  per  indicated  HP,  giving  9  HP  upon 
the  dynamometer,  and  28  cubic  feet  per  dynomemetric  horse. 

Experiments  made  at  the  Crystal  Palace  Electrical  Exhibition, 
in  1 88 1,  with  a  12  HP  engine  gave  a  maximum  brake  power  of 
18-3  HP,  with  a  gas  consumption  of  237  cubic  feet  per  IHP,  and 
29-1  cubic  feet  per  brake  HP.  With  a  two-horse  engine,  2-87 
brake  horse  was  obtained  upon  33*4  cubic  feet  per  horse  hour, 
and  27-9  cubic  feet  per  indicated  horse  hour. 

The  consumption  running  without  load  does  not  seem  to  have 
been  taken  in  these  tests. 

The  author  has  taken  the  consumption  of  a  two-horse  engine 
running  without  load  in  London,  at  160  revolutions  per  minute,  as 
32  cubic  feet  per  hour,  and  a  3-5  horse  engine  without  load  at 
1 66  revolutions  per  minute  as  43  cubic  feet  per  hour. 

The  Messrs.  Crossley  give  the  following  as  the  results  with 
their  new  Otto  twin  engine  rated  at  12  HP  : 

Power  by  dynamometer        .         .         .„...,         .23  horse. 

Power  indicated  in  cylinders          .         .         .         '.28  horse. 

Gas  consumption  per  indicated  H-P       .         .         .20  cb.  ft.  per  hour. 

Gas  consumption  per  effective  HP         .         .         .     24-3  cb.  ft   per  hour. 

Taal  consumption  at  full  power  .         .         «         .     560  cb.  ft.  per  hour. 

Total  consumption  when  lunning  without  load  at 

160  revs,  per  minute 100  cb.  ft.  per  hour. 


Gas  Engines  of  Different  Types  in  Practice         1 81 


txo 

c 
W 


182  The  Gas  Engine 

These  results  are  obtained  using  Manchester  gas. 
Mr.  G.  H.  Garrett  has  made  a  trial  with  an  8  HP  Otto  engine 
in  Glasgow,  the  diagram  and  particulars  of  which  are  given  on 

ng-  55- 

Summary  of  Experiments. — From  these  numerous  and  careful 
experiments,  conducted  quite  independently  of  each  other  by 
many  observers,  it  may  be  taken  as  abundantly  established  that 
the  Otto  engine  is  a  great  advance  in  economy  and  certainty  of 
action  upon  any  gas  engine  preceding  it.  On  the  Continent  and 
in  America  the  consumption  per  horse  power  hour  is,  on  the 
whole,  greater  than  in  Britain  ;  this  is  due  not  to  any  appreciable 
difference  in  the  efficiency  of  the  engines  made  here,  but  to  the 
better  gas  common  in  this  country. 

Calculations  of  the  efficiency  attained  in  some  of  the  later  engines 
in  England,  show  that  as  much  as  18  per  cent,  of  the  heat  is  con- 
verted into  work  as  shown  by  the  indicator.  Dr.  Slaby's  value  is 
1 6  per  cent.,  and  Professor  Thurston's  17  per  cent.  All  observers 
agree  that  the  heat  liberated  at  the  moment  of  completed  explosion, 
that  is,  of  highest  temperature,  is  roughly  one-half  of  the  total  heat 
present  as  coal  gas,  the  remaining  half  being  evolved  during  the 
expansion  period.  Professor  Thurston  gives  the  heat  of  the  ex- 
plosion as  60  per  cent,  of  the  total  heat  present,  Dr.  Slaby  as  55 
per  cent.  The  author's  experiments  upon  the  heat  evolved  by 
the  explosion  of  different  mixtures  of  gas  and  air,  show  heat 
accounted  for  by  the  explosion  as  ranging  from  50  to  60  per  cent., 
agreeing  with  the  determinations  of  Bunsen,  Him,  Mallard  and 
Le  Chatelier,  and  Berthelot  and  Vieille.  It  may  therefore  be 
considered  as  absolutely  proved  that  this  suppression  of  heat  at 
explosion,  and  its  evolution  during  expansion,  is  a  phenomenon 
inherent  in  every  explosive  mixture,  however  made— a  thing,  in 
fact,  from  which  there  is  no  escape.  In  whatever  way  an  engine 
be  made,  if  it  explodes  or  burns  a  mixture  of  any  inflammable 
gas  with  any  mixture  of  gases  containing  oxygen,  then  this  slow 
combustion  or,  as  the  Germans  have  it,  nachbrennen  (after-burn- 
ing) is  unavoidably  occasioned.  Knowing  this,  and  knowing  of 
Him,  Bunsen,  and  Mallard  and  Le  Chatelier's  work  long  prece- 
dent to  Dr.  Slaby's  report,  it  is  surprising  to  find  so  able  and 
learned  a  scientist  quoted  as  stating  that  in  the  Lenoir  engine 


Gas  Engines  Of  Different  Types  in  Practice         183 

the  whole  heat  was  evolved  at  the  moment  of  complete  explosion. 
In  the  Lenoir,  as  in  every  other  gas  engine  which  has  ever 
been  constructed,  not  more  than  one-half  of  the  whole  heat  of 
the  gas  present  is  then  evolved,  the  remaining  heat  being  evolved 
on  the  expanding  stroke. 

Schottler  falls  into  the  same  error,  and,  although  mentioning 
Wedding's  statement  of  Bunsen's  law  of  dissociation,  shows  that 
he  rejects  it  when  he  assumes  that  the  whole  heat  is  evolved.  A 
very  cursory  examination  of  the  Lenoir  diagram  would  at  once 
prove  to  Prof.  Schottler  that  Lenoir  did  not  succeed  in  so 
escaping  the  laws  of  nature ;  had  .he  done  so,  there  would  have 
been  no  necessity  for  our  modern  improvements. 

The  consumption  of  continental  gas  may  be  taken  as  varying 
between  32  cb.  ft.  and  35  cb.  ft.  per  effective  HP  per  hour,  and 
about  28  cb.  ft.  per  I  HP  per  hour. 

In  Britain  it  may  be  taken  as  ranging  from  24  cb.  ft.  pet 
effective  HP  to  33  cb.  ft.,  and  20  to  24  cb.  ft.  per  IHP  per  hour, 
depending  upon  the  quality  of  gas  used  and  on  the  dimensions 
of  the  engine  tested.  Other  things  being  equal,  better  results 
are  obtained  with  large  engines.  The  theoretic  efficiency  is  con- 
stant for  both  large  and  small  engines  where  the  same  compression 
is  in  use,  but  the  loss  of  heat  from  the  explosion  to  the  sides  of 
the  cylinder  is  less  in  the  large  engines,  due  to  the  diminished 
surface  exposed  in  proportion  to  the  volume  used.  The  effect  is 
to  increase  the  efficiency  of  the  gas  in  the  mixture  used,  -a 
smaller  quantity  being  necessary  to  make  up  for  the  loss  of 
heat. 

The  indicator  diagrams  prove  the  very  efficient  nature  of  the 
Otto  cycle.  The  great  simplicity  attained  by  the  alternate  use  of 
the  cylinder  as  pump  and  motor  diminishes  the  number  of  valves 
necessary,  and  secures  the  minimum  resistance  to  the  entering 
gases,  while  entirely  preventing  any  loss  due  to  ports,  in  trans- 
ferring the  gases  from  one  cylinder  to  another.  The  carrying  out 
of  the  cycle  is  mechanically  almost  perfect,  no  work  being  spent 
which  is  not  included  in  the  theory..  -  Again,  the  piston  is  full  in 
at  the  moment  of  ignition  and  is  almost  at  rest  ;  the  heat,  pro- 
ducing maximum  temperature,  is  therefore  added  at  nearly 
constant  volume.  The  highest  pressure  which  the  gas  present  is 


1 84  The  Gas  Engine 

capable  of  producing  is  therefore  attained  at  the  beginning  of  the 
stroke  simultaneously  with  the  highest  temperature  ;  the  succeed- 
ing expansion  is  then  very  rapid,  and  so  no  unnecessary  waste  of 
heat  occurs,  the  temperature  being  rapidly  depressed  by  work 
being  done.  The  united  effect  of  all  the  arrangements  is  seen  in 
a  diagram  which  is  almost  theoretically  perfect  ;  the  only  de- 
duction from  theory  is  due  to  the  unfortunate  property  of  explo- 
sive mixtures  of  continued  combustion  after  explosion.  And 
this  reduces  the  theoretic  efficiency  to  one-half  in  practice.  The 
theoretic  efficiency  of  all  Otto  engines,  of  whatever  dimension,  is 
o'33,  as  the  compression  space  in  all  cases  bears  nearly  the  ratio 
of  o'6  to  i'o  when  compared  with  the  cylinder  volume  which  is 
swept  by  the  piston.  The  actual  indicated  efficiency  is  very 
nearly  one-half  of  that  number. 

If  combustion  by  any  means  could  be  made  complete  at  the 
highest  temperature  and  pressure  at  the  beginning  of  the  stroke, 
instead  of  continuing  as  it  does  well  into  the  expansion  stroke, 
then  greatly  increased  economy  would  result,  and  in  large  engines 
theory  might  be  very  nearly  approached. 

This  point  will  receive  further  discussion  later  on. 

Clerk  Engine. — Otto's  method  is  probably  the  readiest  and 
easiest  solution  of  the  problem  of  attaining  in  a  practicable 
manner  the  advantages  of  compression  ;  in  some  points,  however, 
the  advantages  are  accompanied  with  compensating  disadvantages. 

Only  one  impulse  for  every  two  revolutions  is  obtained  ;  the 
engine  is  therefore  stronger  and  heavier  than  need  be  if  impulse 
every  revolution  were  possible.  It  is  also  more  irregular  in  its 
action  than  more  frequent  impulses  would  give. 

The  Clerk  engine  was  invented  by  the  author  with  the  view  of 
obtaining  impulse  at  every  revolution,  while  getting  at  the  same 
time  the  economy  due  to  compression. 

At  first  blush  it  seems  a  very  simple  matter  to  make  a  com- 
pression gas  engine  to  give  an  impulse  for  every  revolution  ;  this 
was  the  author's  opinion  when  he  commenced  work  for  the  first 
time  upon  gas  engines,  using  compression  in  October  1876.  Since 
then  he  has  had  occasion  to  modify  the  opinion  ;  the  difficulties 
are  very  great ;  any  engineer  who  doubts  this  will  speedily  be 
convinced  upon  making  the  attempt. 


Gas  Engines  of  Different  Types  in  Practice         185 

It  was  not  till  the  end  of  1880  that  the  author  succeeded  in 
producing  the  present  Clerk  engine;  before  that  time  he  had 
several  experimental  engines  under  trial,  one  of  which  was  ex- 
hibited at  the  Royal  Agricultural  Society's  show  at  Kilburn  in 
July  1879.  This  engine  was  identical  with  the  Lenoir  in 
idea,  but  with  separate  compression  and  a  novel  system  of 
ignition. 

The  Clerk  engine  at  present  in  the  market  was  the  first  to 
succeed  in  introducing  compression  of  this  type,  combined  with 


FIG.  56.— The  Clerk  Gas  Engine. 

ignition  at  every  revolution  ;  many  attempts  had  previously  been 
made  by  other  inventors,  including  Mr.  Otto  and  the  Messrs. 
Crossley,  but  all  had  failed  in  producing  a  marketable  engine. 
It  is  only  recently  that  the  Messrs.  Crossley  have  made  the  Otto 
engine  in  its  twin  form  and  so  succeeded  in  getting  impulse  at 
every  turn. 

In  the  Clerk  engine  the  whole  cycle  is  completed  in  one  re- 
volution, and  an  impulse  given  to  the  crank  on  every  forward 
stroke  of  the  piston,  when  working  at  full  power. 

The  engine  contains  two  cylinders,  one  for  producing  power, 


1 86  The  Gas  Engine 

the  other  for  taking  in  the  combustible  charge  and  transferring  it 
to  the  power  cylinder.  At  the  end  of  the  motor  cylinder  is  left 
a  compression  space  of  a  conical  shape,  and  communicating  with 
the  charging  or  displacing  cylinder  by  a  large  automatic  lift-valve 
opening  into  the  space  ;  at  the  other  end  of  the  cylinder  are  placed 
V-shaped  ports  opening  to  the  atmosphere  by  the  exhaust  pipe  ; 
the  motor  piston,  when  near  its  outer  limit,  overruns  these  ports 
and  allows  the  cylinder  to  discharge.  The  pistons  are  connected 
in  the  usual  manner  by  connecting  rods,  the  motor  to  the  main  crank 
of  the  engine,  the  displacer  to  a  crank  pin  in  one  of  the  arms  of 
the  fly-wheel;  the  displacer  crank  is  in  advance  of  the  motor  crank, 
in  the  direction  of  motion  of  the  engine,  by  a  right  angle.  The 
displacer  piston  on  its  forward  movement  takes  in  its  charge  of 
gas  and  air,  and  has  returned  a  fraction  of  its  stroke  when  the 
motor  piston  uncovers  the  exhaust  ports.  While  crossing  the  centre, 
opening  and  shutting  these  ports  the  displacer  piston  has  moved 
in  almost  to  the  end  of  its  cylinder,  discharging  its  contents 
into  the  space  and  forcing  out  at  the  exhaust  ports  the  products  of 
the  previous  ignition.  The  proportions  of  the  two  cylinders  are  so 
arranged  that  the  exhaust  is  as  completely  as  possible  expelled, 
and  replaced  by  cool  explosive  mixture,  which  thoroughly  mixes 
with  any  exhaust  remaining,  cooling  it  also  to  a  considerable 
extent.  Care  must  be  taken  in  the  arrangement  of  the  parts 
that  an  excessive  volume  is  not  sent  from  the  displacer, 
otherwise  it  may  reach  the  exhaust  ports  and  gas  discharge 
unburned. 

The  return  stroke  of  the  motor  piston  now  compresses  the 
mixed  gases,  and  when  at  the  extreme  end,  the  igniting  valve  fires 
the  mixture,  the  piston  moves  forward  under  the  pressure  thereby 
produced,  till  the  opening  of  the  exhaust  ports  causes  discharge 
and  replacement  as  before.  In  this  way  an  impulse  is  given  at 
every  revolution,  and  the  motive  power  applied  to  greater  advantage. 
The  motor  cylinder  is  surrounded  by  water  for  cooling,  but  this 
is  unnecessary  with  the  displacer,  as  it  uses  only  cool  gases.  The 
pressures  used  are  high,  so  that  both  motor  piston  and  its  connec- 
tions are  made  very  strong ;  the  pressure  on  the  displacer  piston 
is  very  little,  so  the  connections  are  light.  It  is  not  a  compressing 
pump,  and  is  not  intended  to  compress  before  introduction  Jnto 


Gas  Engines  of  Different  Types  in  Practice         187 

the  motor,  but  merely  to  exercise  force  enough  to  pass  the  gases 
through  the  lift  valve  into  the  motor  cylinder,  and  there  displace 
the  burnt  gases,  discharging  them  into  the  exhaust  pipe.  The 
pressure  to  be  overcome  is  only  that  due  to  resistance  in  the 
exhaust  pipes  and  the  lift  valve. 

The  inlet  valve  for  gas  and  air  is  also  automatic ;  its  seat  is  of 
the  usual  conical  kind  but  somewhat  broad.  A  gutter  runs  round 
the  centre,  having  small  holes  bored  through  to  a  recess  behind, 


FIG.  57. — Longitudinal  Section  of  Clerk  Gas  Engine. 

which  communicates  with  the  gas  supply  pipe.  The  suction  lifts  the 
valve  to  a  certain  height,  and,  as  the  gases  enter,  the  air  flows  past 
the  holes  and  becomes  thoroughly  impregnated  with  gas,  the 
extent  being  determined  by  the  number  of  holes  and  the  propor- 
tion of  their  area  to  the  total  area  of  the  valve  opening.  The 
upper  valve  is  made  heavy  to  withstand  the  maximum  pressure  of 
the  explosion ;  both  valves  are  arranged  so  that  the  guide  forms 


1 88  The  Gas  Engine 

a  piston  working  in  an  air  cylinder,  so  arranged  as  to  check 
the  fall  of  the  valve  before  touching  the  seat,  and  so  prevent  any 
disagreeable  rattle. 

Description  of  the  Drawings. — Fig.  56  is  a  general  view  of  the 
engine.  Fig.  57  a  longitudinal  section.  Fig.  58  a  sectional  plan. 
In  these  drawings  all  the  essential  parts  of  the  engine  are  repre- 
sented ;  the  sectional  plan  (fig.  58)  shows  the  two  cylinders, 
motor  A  and  displacer  B,  in  which  work  the  pistons  c  and  D 
suitably  connected  to  cranks  not  shown  in  the  drawing,  but  on  a 
common  crank  shaft.  The  motor  crank  is  double  and  of  great 
strength  ;  the  displacer  crank  pin  is  fixed  into  an  arm  in  the  fly- 
wheel, and  in  the  direction  of  motion  of  the  engine  is  a  half  right 
angle  or  quarter  circle  in  advance.  The  motor  piston  is  shown  at 
its  extreme  out-stroke,  having  passed  over  the  exhaust  ports  E  E1, 
the  piston  thus  serving  as  its  own  exhaust  valve,  and  dispensing 
with  any  other,  as  shown  ;  the  displacer  piston  has  moved  half  in 
and  discharged  a  portion  of  the  contents  through  the  valve  F 
(more  distinctly  seen  in  the  other  section,  fig.  57)  into  the  conical 
space  G,  which  is  so  proportioned  that  the  entering  gases  push 
before  them  the  burned  gases  through  the  ports  referred  to,  but 
without  following  them  into  these  ports.  By  the  continued  move- 
ment, all  the  gases  in  B  pass  into  A  and  the  space  G;  the  capacities 
of  the  two  cylinders  are  so  related  that  as  much  as  possible  of  the 
burnt  gases  is  discharged  into  the  atmosphere,  but  without  carrying 
away  any  of  the  fresh  mixture  containing  unburned  gas;  this  neces- 
sitates the  mixture  next  the  piston  being  somewhat  more  dilute 
than  that  next  the  inlet  valve,  but  the  commotion  occasioned  by 
compression  so  far  equalises  this  undesirable  state  of  things  that  at 
half  in-stroke  the  mixture  in  its  weakened  portions  is  quite  capable 
of  inflammation  by  a  light  or  the  electric  spark.  The  piston  D 
having  completed  its  in-stroke,  c  has  passed  over  the  discharge 
ports  and  compresses  the  contents  of  the  cylinder  into  the  space  G; 
when  full  in  and  therefore  completely  compressed,  the  slide  valve 
M  has  moved  into  such  a  position  as  to  ignite  the  mixture  ;  the 
maximum  pressure  being  attained  very  rapidly  and  before  the 
piston  can  move  appreciably  on  its  out-stroke,  the  piston  is  impelled 
forward  under  the  pressure  produced  until  it  reaches  the  ports  E  E1, 
when  the  contents  are  rapidly  discharged,  and  the  interior  and 


Gas  Engines  of  Different  Types  in  Practice 


I 


190 


The  Gas  Engine 


exterior  pressures  equalised.  Meantime  the  piston  D  being  in 
advance  of  the  motor  has  moved  to  the  end  of  its  stroke  and  is 
beginning  to  return,  it  has  charged  the  cylinder  B  with  a  mixture 
of  gas  and  air  from  the  automatic  valve  H  (fig.  57),  the  commu- 
nication being  made  by  the  pipe  w  (fig.  58).  In  the  seat  of  this 
valve  are  bored  a  number  of  small  holes  passing  into  the  annular 
?pace  K  K1  (fig.  57),  which  communicates  with  the  gas  cock  L  (fig. 
58)  through  the  passage  shown,  in  which  is  situated  the  lift-govern- 
ing valve,  not  seen.  Under  the  deficit  of  pressure  caused  by  the 


jam*  Upper  lift  valve. 


Quieting  piston. 


Lower  lift  valve. 


-im..  Gas  channel. 


IHll Quieting  piston. 


FIG.  59.— Section  of  Lift  Valves.     Clerk  Engme. 

movement  of  the  displacing  or  charging  piston,  the  valve  is -lifted 
and  the  exterior  atmosphere  rushes  through,  at  the  same  time  the 
gas  passing  through  the  holes  mixes  with  it  thoroughly,  the  pro- 
portion being  determined  by  the  relative  areas  of  the  holes  and 
the  space  available  for  air  by  the  lift  of  the  valve. 

The  gases  in  B  are  under  some  slight  compression  before  the 
complete  discharge  of  A,  but  not  sufficiently  great  to  cause  any 
material  resistance  ;  so  soon  as  the  pressure  under  the  valve  F  is 
slightly  in  excess  of  that  above  it,  then  it  lifts  and  the  gases  pass 
into  G.  The  passage  from  the  valve,  which  may  be  called  the 


Gas  Engines  of  Different  Typvs  in  Practice         191 

upper  lift  valve,  is  more  clearly  seen  in  fig.  57  :  the  igniting  hole 
is  shown  at  N,  and  communicates  at  the  proper  time  with  flame  in 
the  cavity  o,  which  has  been  ignited  at  the  exterior  flame  p,  from 
,1  Bunsen  burner  (fig.  58). 

The  two  automatic  valves  charging  the  displacer  cylinder  and 
discharging  into  the  motor  cylinder  are  provided  with  quieting 
pistons,  cushioning  the  blow  on  the  valve  seat  and  preventing 
rattle  ;  they  are  similar  to  the  dash  pot  contrivances  used  on 
Corliss'  steam  engines  to  check  the  snap  of  the  steam  valves,  but, 
unlike  them,  are  attached  directly  to  the  valve,  instead  of  to  the 
valve  spindle  and  guide.  The  arrangement  is  very  clearly  seen  at 
fig.  59 :  the  lower  valve  has  no  spring,  it  returns  to  its  seat  by  its 
own  weight ;  but  the  upper  valve  requires  to  act  more  quickly 
and  is  pulled  down  by  a  spring. 

The  piston  attached  compresses  the  air  before  it,  and  the 
valve  strikes  its  seat  rapidly  but  without  jar  or  recoil. 

The  igniting  slide,  M,  is  driven  from  an  eccentric  on  the  crank 
shaft  through  a  bell  crank  and  guide. 

Diagrams  and  Gas  Consumption. — The  following  tests  give 
the  latest  results  from  the  Clerk  engine  ;  they  are  the  usual  trials 

TESTS  OF  THE  CLERK  ENGINES  OF  VARIOUS  POWERS. 


2  HP 

4  HP 

6  HP 

8  HP 

12  HP 

Diameter  of  motor  cylinder    •   .- 

5  ins. 

6  ins. 

7  ins. 

8  ins. 

9  ins.   : 

Stroke         .         .         .';'•; 

8  in*. 

10  ins. 

12  ins. 

16  ins. 

20  ins. 

Diameter  of  displacer  cylinder  . 

6  ins. 

7  ins. 

7k  ins. 

ID  ins. 

10  ins. 

Stroke        .         .         .'.'.. 

9  ins. 

n  ins. 

12  ins. 

13  ins. 

20  ins. 

Average  revs,  per  min.  during  test 

212 

190 

146 

142 

132 

Average  pressure   (available)    in 

motorcylinder  in  Ibs  persq.  in. 
Power  indicated  in  motor  cylinder 

43'2 
3-62 

63-9 
8-68 

53  '2 
9'°5 

60-3 
17-38 

64-8 
27-46 

Power  by  dynamometer     . 

270 

5'63 

7^3 

13-69 

23  21 

Gas  consumption  in  cb.   ft.  per 

IHP  per  hour 

29-8 

24-19 

24'3 

20-94 

20-39 

Gas  consumption  per  brake  HP 

hour 

4O  'O 

07  "* 

•2O"42 

26-58 

24'12 

Max.  pressure  of  explosion  in  Ibs. 

T-W  *-* 

o/  $ 

O        T" 

per  sq.  in.  above  atmos. 

155  Ibs. 

236 

r95 

195 

238 

Pressure  of  compression  in  Ibs. 

per  sq.  in.  above  atmos. 

38  Ibs. 

55 

48 

49 

57 

Displacer  resistance  . 

0-40 

o'8o 

0-86 

1-50 

2'OO 

Gas  consumed  per  hour  bv  each 

engine  at  speed  without  load  . 

40  cb  ft. 

58  cb.  ft. 

57  cb.  ft. 

70  cb.  ft. 

90  cb.  ft. 

The  Gas  Engine 


made  by  Messrs.  L.  Sterne  and  Co.  on  all  engines  before  leaving 
the  works,  and  therefore  represent  fairly  the  economy  to  be 
expected  from  these  engines  in  ordinary  work.  They  are  from 
2,  4,  6.  8,  and  12  HP  engines  (nominal).  The  trials  were  made 
during  1885  at  the  Crown  Iron  Works,  Glasgow,  under  the 
direction  of  Mr.  G.  H.  Garrett. 

Figs.  60,  6 1,  62  are  fair  samples  of  the  diagrams  taken  during 
the  tests.  Figs.  63  and  64  are  diagrams  from  the  displacers 
showing  the  displacer  resistance. 


Nominal  HP,  6  ;  diam.  of  cylinder,  7"  ;  length  of  stroke,  12"  ;  No.  of  revs.  146  ;  in 


FIG.  60.—  Diagram  from  Clerk  Gas  Engine,  6  HP. 

Calculating  from  these  diagrams  the  actual  indicated  efficiency 
it  comes  to  16  per  cent,  of  the  total  heat  given  to  the  engine. 

The  compression  space  in  the  Clerk  engines  is  as  nearly  as 
possible  one-half  of  the  volume  swept  by  the  piston  from  the 
exhaust  port  to  the  end  of  its  stroke.  The  theoretic  efficiency  is 
therefore 


The  compression  is  higher,  and  therefore  the  tneoretic  efficiency 


CAIIFC^ 


Gas  Engines  of  Different  Types  in  Practice         193 

of  this  engine  is  higher  than  the  Otto,  but  the  difficulties  of  pro- 
portioning the  two  cylinders  of  the  Clerk  engine  cause  a  small 
loss  of  unburned  gas  at  the  exhaust  ports,  so  that  the  actual 
efficiency  is  similar  to  that  of  Otto. 

The  mixture  sent  from  the  displacer  cylinder  into  the  motor 
and  the  space  at  the  end  of  it,  contains  8  vols.  of  air  with 
i  vol.  of  coal  gas,  but  on  passing  through  the  upper  lift  valve 
and  mixing  to  some  extent  with  the  exhaust  there  contained,  it 
is  somewhat  diluted ;  the  heat  acquired  by  contact  with  the 
products  of  combustion  and  with  the  sides  of  the  cylinder  expands 
the  entering  gases,  and  a  temperature  of  not  less  than  100°  C.  is 


Nominal  HP,  8  ;  diam.  of  cylinder,  8'' ;  length  of  stroke,  16"  ;  No.  of  revs.  142  : 
indicated  HP,  17*38;  consumpt.  per  IHP,  20*94  CD-  ft-  '  consumpt.  running  light 
per  hour,  70  cb.  ft.  ;  brake  HP,  13*69  ;  consumpt.  per  BHP,  26*58  cb.  ft.  ;  mean 
pressure,  60*3  Ibs.  ;  max.  pressure,  195  Ibs. ;  pressure  before  ignition,  49  Ibs.  ;  scale 
of  spring,  yj^"  per  Ib. 

FIG.  61. — Diagram  from  Clerk  Gas  Engine,  8  HP. 

attained  before  the  compression  commences.  The  result  of  this 
is,  that  the  displacer  gases,  being  expanded,  expel  more  of  the 
exhaust  gases  through  the  discharge  ports  than  would  appear 
from  the  volume  swept  by  the  displacer  piston.  This  volume  is 
equal  to  the  volume  swept  by  the  motor  piston,  from  closing  of 
the  exhaust  ports  to  complete  in-stroke.  If  no  expansion  and  no 
mixing  occurred,  the  exhaust  gases  contained  in  the  compression 
space  would  remain  in  front  of  the  cooler  explosive  charge ;  but 
the  heat  increases  the  volume  at  least  one-third,  so  that  the 

o 


194 


The  Gas  Engine 


volume  occupied  will  be  i^  times  the  volume  swept  by  either 
piston.     The  volume  of  cylinder  plus  space  is  i^  vol.  of  cylinder, 


18J 


8.. 


«   C3   3 

«•:.£  a 


O    V 


tn  w 


„ 

=11* 

" 


so  that  the  actual  exhaust  gases  present  are  J  vol.,  or  Ty  of  the 
total  gases  present.  But  mixing  must  occur  to  a  considerable 
extent  and  be  made  very  complete  on  the  return  stroke  during 


Gas  Engines  of  Different  Types  in  Practice         195 

compression.  The  result  of  all  this  is  the  production  of  an  explosive 
mixture  which  is  explosive  in  every  part  of  it,  and  of  an  average 
composition  of  one  volume  of  coal  gas  in  ten  of  the  mixture. 
The  proportion  of  burned  gases  present  is  very  slight ;  the  only 
reason  why  any  should  be  left  is  the  necessity  of  preventing  any 


PH 

M 
&o 

I 

cT 

w 

u 


~ 

&  a 


appreciable  discharge  of  unburned  gas  at  the  exhaust  ports.     The 
mixture  used  is  a  comparatively  rich  one. 

Tangye  Engine. — Messrs.  Tangye,  of  Birmingham,  have  pro- 
duced an  engine  in  which  compression  of  the  kind  common  to  the 
third  type  is  used  and  an  ignition  is  obtained  for  every  revolution 


O  2 


The  Gas. Engine 

when  at  full  power.  It  is  Robson's  patent  and  contains  only  one 
cylinder.  All  the  necessary  operations  of  charging,  compressing, 
and  igniting  are  fulfilled  with  one  cylinder  ;  it  is  arranged  as  in  an 
ordinary  steam  engine.  The  front  end  of  the  cylinder  unlike  the 
Otto  and  Clerk  engines  is  closed,  the  piston  being  provided  with 
a  piston  rod,  cylinder  cover,  and  stuffing  box,  as  in  steam.  The 
front  end  of  the  cylinder  serves  for  charging,  the  back  end  for 
compression  and  explosion. 

There  is  a  compression  space  at  the  back  end  of  the  cylinder  as 
in  the  other  engines. 

The  action  is  as  follows.  During  the  return  stroke,  gas  and 
air  mixture  is  drawn  into  the  front  end  of  the  cylinder  at  atmo- 


FIG.  65. — Robson's  Gas  Engine. 

spheric  pressure,  through  an  automatic  valve.  The  next  out-stroke 
compresses  the  mixture  into  a  large  intermediate  chamber  at  a 
pressure  of  not  more  than  five  Ibs.  per  sq.  in.  above  atmosphere. 
When  full  out  and  the  exhaust  ports  therefore  open,  this  pressure 
lifts  a  valve  leading  into  the  compression  space  of  the  engine,  dis- 
charging before  it  the  gases  contained  in  the  cylinder  through  the 
exhaust  valve  and  filling  the  cylinder  and  space  with  explosive 
mixture.  This  reduces  the  pressure  in  the  intermediate  reservoir 
to  atmosphere  so  that  the  next  in-movement  of  the  piston  com- 
presses the  explosive  mixture  upon  one  side  of  the  piston  and  takes 
in  fresh  mixture  on  the  other  side. 


Gas  Engines  of  Different  Types  in  Practice         197 

When  compression  is  completed  the  igniting  valve  acts  and  the 
explosion  impels  the  piston ;  so  soon  as  the  exhaust  ports  open,  the 
pressure  falls  to  atmosphere,  and  then  the  reservoir  pressure  bein*>- 
superior  to  that  in  the  cylinder,  the  automatic  valve  acts  and  the 
fresh  charge  enters. 

Thus  an  explosion  is  obtained  at  every  revolution  by  using  the 
front  end  of  the  cylinder  as  displacer  and  storing  up  the  pressure 
in  an  intermediate  reservoir. 

The  governing  is  managed  by  cutting  oft"  gas  supply,  but  is 
hampered  considerably  by  the  intermediate  chamber.  Fig.  65 
is  an  external  view  of  the  engine,  which  is  exceedingly  neat  and 
of  substantial  workmanship. 

The  Stockport  Engine. — This  engine  is  similar  to    Robson's 


FIG.  66.— The  Stockport  Gas  Engine. 

in  theory  but  the  front  end  of  the  cylinder  is  not  used  for  charg- 
ing, the  piston  being  made  a  double  trunk  with  the  crank  be- 
tween, and  one  end  and  one  cylinder  being  motor,  the  other  end 
and  the  other  cylinder  being  displacer.  Compression  occurs  in 
the  motor  cylinder.  Fig.  66  shows  the  external  appearance.  The 
valve  arrangements  differ  from  those  of  Messrs.  Tangye.  It  is 
made  by  Messrs.  Andrew,  of  Stockport. 

Atkinson's  Differential  Engine.— -The  description  of  engines  of 
this  type  would  be  incomplete  without  mention  of  this  engine, 
exhibited  at  the  Inventions  Exhibition  for  the  first  time  in  1885. 
It  is  exceedingly  ingenious  and  quite  novel. 


198 


The  Gas  Engine 


Fig.  67  is  an  elevation,  fig.  68  a  section,  and  fig.  69  a  plan. 
The  action  is  very  clearly  seen  from  the  different  positions  on  fig. 
70. 

The  same  cylinder  serves  for  all  purposes  of  the  cycle  ;  two 
trunk  pistons,  working  in  opposite  ends  of  it  are  connected  to 


ELEVATION 


FIG.  67.— Atkinson's  Differential  Gas  Engine. 

the  levers  and  from  thence  to  the  crank  shaft  by  the  connecting 
rods.     The  short  rods  cause  the  necessary  actions. 

In  the  first  position,  fig.  70,  the  pistons  are  at  one  extreme  of 
their  stroke,  and  are  just  beginning  to  separate.     The  charge  of  gas 


Gas  Engines  of  Different  Types  in  Practice         199 

and  air  enters  between  them  through  the  automatic  lift  valve,  and 
in  position  2,  the  charge  has  entered  and  the  further  movement 
of  the  piston  is  about  to  close  the  port  leading  to  the  admission 
and  exhaust  valves.  The  compression  thus  commences  and  in 
position  3  it  is  completed.  The  ignition  occurs  and  the  pistons 


SECTION 


FIG.  68.  —Atkinson's  Differential  Gas  Engine. 

now  rapidly  separate,  the  exhaust  port  being  uncovered  and  the 
discharge  commencing  in  position  4.  By  this  clever  method 
the  whole  operations  of  admission,  discharge,  ignition,  and  expan- 
sion are  performed  in  the  single  cylinder  with  only  two  automatic 


2OO 


TJie  Gas  Engine 


FIG.  69. — Atkinson's  Differential  Gas  Engine. 


FIG.  70.— Atkinson's  Differential  Gas  Engine. 


Gas  Engines  of  Different  Types  in  Practice         201 

valves  which  are  never  exposed  to  the  pressure  of  explosion,  the 
pistons  acting  in  some  part  as  valves  and  uncovering  the  exhaust 
and  inlet  ports  when  required.  In  the  other  extreme  position  they 
also  act  as  valves,  the  outside  piston  uncovering  the  igniting  port 
at  the  correct  time.  Sufficient  experience  has  not  yet  been  accu- 
mulated with  this  engine  to  speak  positively  as  to  its  performance. 
To  the  author,  the  principal  disadvantage  appears  to  lie  in  a  com- 
pression space  of  diameter  so  great,  in  proportion  to  depth,  that  the 
ratio  of  cooling  surface  to  volume  of  hot  gases  is  largely  in  excess 
of  that  common  to  other  engines.  This  disadvantage  will  diminish 
the  economy  which  the  great  expansion  would  otherwise  give. 


202  The  Gas  Engine 


CHAPTER   VIII. 

IGNITING   ARRANGEMENTS. 

HOWEVER  perfect  the  theoretic  cycle  of  an  engine,  or  however 
admirable  is  its  construction,  in  the  absence  of  a  good  igniting 
valve  the  skill  and  energy  expended  is  of  no  avail.  The  engine 
is  a  useless  mass  of  metal  requiring  power  to  move  itself  rather 
than  furnishing  power  to  set  other  machines  in  motion. 

In  the  earlier  stages  of  gas  engine  manufacture,  the  igniting 
method  has  been  the  most  fruitful  source  of  annoyance  and  diffi- 
culty ;  even  yet,  after  many  years  of  engineering  experience,  the 
igniting  valve  is  still  the  initial  difficulty  which  the  inventor  must 
overcome  before  he  gets  the  opportunity  of  testing  his  theories  of 
heat  and  work  in  a  moving  machine.  Quite  a  number  of  wit- 
nesses, in  the  shape  of  unworkable  gas  engines,  in  many  engineers' 
workshops  throughout  Britain,  attest  silently  but  emphatically  the 
difficulties  of  the  igniting  valve. 

The  problem  is  by  no  means  a  simple  one,  and  the  care 
lavished  upon  its  solution  would  not  be  suspected  on  inspection 
of  the  igniting  gear  of  any  good  modern  engine.  Much  has  been 
done,  but  much  still  remains  yet  to  be  accomplished  before  flame 
is  as  completely  and  effectively  under  control  as  steam. 

In  the  noncompression  engines  the  problem  is  comparatively 
simple — to  inflame  a  volume  of  explosive  mixture  enclosed  in 
a  cylinder,  so  that  the  explosion  is  confined  within  the  cylinder, 
and  no  communication  is  open  to  atmosphere.  This  is  to  be  re- 
peated regularly  and  with  certainty  at  rates  varying  from  60  to  150 
times  per  minute,  depending  upon  the  speed  of  the  engine.  In 
the  earlier  trials,  what  may  be  called  the  touch  hole  method 
naturally  suggested  itself ;  the  piston  after  taking  in  its  charge, 
crossed  a  small  hole  and  sucked  a  flame  through  it  into  the  cylin- 


Igniting  Arrangements  203 

der,  the  hole  being  either  small  enough  to  occasion  no  substantial 
loss  of  pressure  upon  explosion,  or  covered  by  a  small  valve  closing 
with  the  pressure  from  the  interior.  This  is  the  earliest  flame 
method.  Then  comes  the  idea  of  using  the  electric  spark,  and  so 
completely  closing  up  the  cylinder,  and,  later  on,  a  return  to  flame, 
using  a  double  flame,  one  to  ignite  an  intermediate  one,  and 
the  intermediate  flame  carried  in  a  pocket  or  hollow  cock  to  the 
mixture.  Then  the  idea  of  spongy  platinum  suggested  by  the 
well-known  Doberiner's  Hydrogen  lamp.  Later  on  the  heating  of 
metal  tubes  or  metal  masses  and  the  ignition  of  the  gases  by  con- 
tact with  them.  Then  electrical  ignition  again,  but  this  time  by 
iiealing  a  platinum  wire  to  incandescence.  All  those  methods  were 
proposed  and  to  some  extent  practised  long  before  gas  engines 
appeared  in  any  commercially  successful  form. 

Ignition  methods  may  be  classed  in  four  distinct  groups. 

(1)  Electrical  methods. 

(2)  Flame  methods. 

(3)  Incandescence  methods. 

(4)  Methods  depending  on  '  Catalytic  '  or  chemical  action. 

(i)  ELECTRICAL  METHODS. 

Spark  Method. — The  use  of  the  electric  form  of  energy  seems 
at  first  sight  a  very  convenient  and  easy  method  of  getting  an  in- 
tense heat  at  any  desired  time  and  in  any  desired  spot  in  the 
interior  of  a  cylinder.  The  electric  spark  has  long  been  used  by 
chemists  to  explode  the  contents  of  the  eudiometer  in  which  gas 
analysis  is  effected  ;  and  the  platinum  wire  rendered  incandescent 
by  the  current  from  a  battery  has  long  been  familiar  to  experi- 
menters and  is  used  by  them  for  many  purposes.  The  spark 
method  was  used  in  the  Lenoir  engine.  A  Bunsen's  battery,  a 
Rumkorff  induction  coil,  and  a  commutator  or  distributor,  i-s 
required  in  addition  to  the  insulated  points  between  which  the 
spark  passes  in  the  interior  of  the  cylinder. 

Fig.  71  is  drawn  to  show  clearly  the  general  arrangement. 
The  Bunsen's  battery  A  generates  the  current,  which  passes  by  the 
wires  to  the  coil  B,  from  which  the  intensity  current  passes  to  the 
insulated  points  D  D  by  way  of  the  distributor  c.  The  negative 
pole  of  the  coil  is  permanently  connected  to  any  part  of  the  metal 


204 


T/ie  Gas  Engine 


work  of  the  engine  ;  the  igniting  points  D,  D,  consist  of  porcelain 
plugs  seen  on  a  larger  scale  at  E.  The  porcelain  is  firmly 
cemented  into  the  brass  nut  i,  and  the  wire  2  which  passes  through 
a  hole  in  the  plug  terminates  outside  in  the  connecting  screw  3, 
and  inside  is  bent  over  the  end  of  the  plug ;  the  other  wire  4, 
passes  through  another  hole  in  the  plug,  is  bent  over  in  the  insid  ; 
lying  near  the  wire  2  but  not  touching  it,  it  then  passes  through 
the  side  of  the  plug  touching  the  metal  of  the  nut.  When  the 
nut  is  screwed  into  position  the  one  wire  is  in  metallic  connec- 
tion with  the  cylinder  of  the  engine,  and  the  other  is  insulated 
from  it. 


FIG.  71. — Ignition  Arrangements  Lenoir  Engine. 

The  distributor  c  consists  of  an  insulated  metallic  arm  i  rota- 
ting on  the  end  of  the  crank  shaft  over  the  insulated  ring  2,  which 
is  connected  to  the  positive  pole  of  the  coil.  Two  insulated  seg- 
ments 3,  4,  are  connected  by  wires  to  the  igniting  plugs  D,  D  ;  in 
rotating,  the  arm  i  comes  alternately  over  3,  4,  and  it  is  within 
sparking  distance  of  the  ring  2  as  well  as  the  segments ;  the  sparks 
pass  alternately  to  the  segments  and  thence  alternately  to  the 
opposite  ends  of  the  cylinder.  The  ebonite  disc  carrying  the  seg- 
ments and  ring  is  so  adjusted  that  the  spark  begins  to  pass  at  either 
end,  just  as  the  admission  valve  closes.  If  it  passed  too  soon  the 


Igniting  Arrangements  205 

explosion  would  occur  before  the  admission  valve  closed,  and 
therefore  would  partly  be  lost,  and  at  the  same  time  would  make  a 
disagreeable  noise.  If  it  is  passed  too  late,  power  is  lost,  because 
the  piston  is  at  its  most  rapid  rate  of  movement  and  is  reducing 
the  pressure  of  the  cylinder  contents  uselessly. 

Notwithstanding  the  most  careful  adjustment,  some  time 
elapses  between  the  closing  of  the  admission  valve  and  the  explo- 
sion. When  all  is  in  good  order  this  arrangement  works  very  well, 
but  should  the  insulation  be  disturbed  and  any  short  circuiting 
occur,  the  spark  fails  to  pass  between  the  points  in  the  interior  of 
the  cylinder  and  a  missed  or  late  ignition  results.  This  often 
happens  in  starting  the  engine  when  it  is  cold ;  the  first  few  explo- 
sions cause  a  condensation  of  water  upon  the  points  and  the  spark 
(hen  fails,  the  current  passing  through  the  water  film  from  wire  to 
wire  without  spark.  The  igniters  then  require  to  be  uncoupled 
and  dried.  To  reduce  this  trouble,  the  points  are  kept  towards 
the  top  of  the  cylinder  in  the  end  covers  so  that  any  water  or  oil 
drainage  may  flow  down  and  leave  them  dry.  The  difficulties  of 
insulation,  coil  and  battery,  are  so  great  that  they  did  much  to 
prevent  the  use  of  the  Lenoir  engine  ;  unless  the  machine  fell  into 
intelligent  hands  it  was  sure  to  go  wrong  and  give  trouble. 

The  spark  method  has  never  been  applied  to  compression 
engines  as  the  compression  increases  all  difficulties.  The  Lenoir 
igniting  plug,  or  '  inflamer '  as  it  was  called,  if  put  in  a  compression 
engine  leaks  badly  and  cannot  be  got  to  act  efficiently.  Many 
specifications  of  compression  and  other  engines  state  that  ignition 
is  accomplished  by  the  electrical  spark,  but  the  Lenoir  engine  alone 
attained  any  success. 

Incandescent  Wire  Method. — This  method  very  naturally  suggests 
itself  as  a  solution  of  the  difficulties  of  the  high  tension  spark;  the 
coil  is  dispensed  with  and  the  current  from  the  battery  is  applied 
directly  to  heat  a  thin  platinum  wire.  The  difficulty  of  insulating  is 
very  slight.  The  tension  being  low  it  is  a  matter  of  indifference 
whether  the  insulating  material  is  wetted  or  not.  The  wire  being 
constantly  at  a  red  heat  cannot  remain  at  all  times  in  the  cylinder, 
but  is  put  into  communication  with  it  at  proper  times  by  means  of 
a  slide  valve.  Fig.  7  2  is  a  drawing  of  an  igniting  slide  of  this  kind, 
as  used  by  the  author  in  experimental  work.  It  acts  very  well  in- 


206 


The  Gas  Engine 


deed.  The  screw  i  carries  the  insulated  rod  2,  insulated  by  means 
of  asbestos  card-board  packed  into  the  space  and  screwed  down 
firmly  by  the  screw  3.  The  other  wire  is  screwed  into  the  metal 
and  so  is  in  metallic  connection  with  the  metal  work  of  the 
engine.  One  wire  from  the  battery  connects  to  any  portion  of  the 
engine  ;  the  other  is  insulated.  The  platinum  wire  4  is  thus  kept 
continually  at  a  red  heat,  and  the  slide  5  moving  at  proper  times 
causes  the  gases  to  be  ignited  to  flow  into  the  chamber  containing 
the  platinum  spiral,  by  the  hole  6,  and  so  causes  the  explosion. 


FIG.  72. — Electrical  Igniting  Valve  (Clerk). 
Incandescent  Platinum  Wire. 

There  is  only  one  precaution  required  in  using  this.  The  battery 
must  not  be  too  powerful  ;  if  the  wire  is  heated  by  it  to  near  its 
fusing  point,  then  the  further  heat  supplied  by  successive  explo- 
sions may  cause  its  destruction.  It  requires  to  be  kept  at  a  good 
red  heat  and  no  more  when  open  to  the  air  :  when  closed  up  and 
in  contact  with  the  hot  gases  it  will  then  become  almost  white  hot  ; 
anything  above  this  may  fuse  it.  The  battery  is  of  course  at  all 
times  a  source  of  care  ;  as  it  requires  to  be  often  renewed,  it  is  only 
for  experimental  work  that  this  arrangement  answers  well.  In  the 
hands  of  the  general  public  it  would  come  to  grief.  Hugon  and 


Igniting  Arrangements  207 

many  others  proposed  similar  arrangements,  but  they  do  not  appear 
to  have  worked  them  out. 

Arc  Method. — There  is  another  electrical  method.  A  small 
dynamo  attached  to  the  engine  keeps  up  a  continuous  current  and 
heavy  platinum  points  in  communication  with  the  cylinder  carry 
the  arc.  This  is  difficult,  however,  as  the  points  constantly  volatilize 
and  require  frequent  renewal.  This  method  has  never  come  into 
practical  use  ;  it  is  described  several  times  in  specifications. 


(2)  FLAME  METHODS. 

The  earliest  really  efficient  igniting  valve  is  that  described  by 
Barnett  in  his  specification  of  1838.  It  is  the  parent  form  of 
the  most  extensively  used  valve,  the  'Otto.' 

Bar  net? s  Igniting  Valve. — Fig.  73  shows  a  vertical  section  and  a 
plan  of  this  valve.  It  consists  of  a  conical  stopcock  with  a  hollow 
plug;  the  shell  contains  two  ports,  i  and  2—1  open  to  the  atmosphere 
and  2  communicating  with  the  cylinder.  The  plug  of  the  cock  has 
one  port,  3,  so  arranged  that  it  may  open  on  the  atmosphere  port  or 
the  cylinder  port  in  the  shell,  but  cover  enough  being  left  to  pre- 
vent it  opening  to  both  at  the  same  time.  In  turning  round  it 
closes  on  tne  atmosphere  before  opening  to  the  cylinder. 

A  gas  jet  burns  at  the  bottom  of  the  shell,  and  in  the  hollow 
of  the  plug,  the  ports  3  and  i  being  long  enough  and  wide  enough 
to  allow  the  air  free  circulation  as  shown  by  the  arrows.  The  flame 
must  not  be  too  large  or  it  will  fill  the  whole  interior  with  gas  and 
prevent  air  getting  in;  the  flame  will  then  burn  at  the  port  i  in  the 
air  and  will  not  enter  the  cock.  Suppose  it  to  be  burning  regu- 
larly in  the  cock  as  shown  in  the  drawing,  then  if  the  plug  is  suddenly 
turned  round  so  that  port  3  closes  upon  the  atmosphere  port  i, 
and  opens  upon  the  cylinder  port  2,  the  air  supply  will  be  sufficient 
to  keep  the  flame  living  till  the  mixture  contained  in  2  reaches  it 
The  explosion  then  occurs.  The  port  2  is  of  the  same  shape  as  i, 
so  that  the  flame  causes  the  gases  to  circulate  the  same  as  the  air 
did  when  open  to  it  ;  the  mixture  comes  in  contact  with  the  flame 
by  circulating  through  the  plug.  If  the  port  2  is  made  so  small 
that  no  circulation  occurs,  then  the  ignition  will  be  a  very  uncer- 
tain matter  ;  as  the  gases  will  require  to  get  at  the  flame  by  difiu- 


203 


The  Gas  Engine 


sion,  which  is  a  slow  process,  and  the  flame  may  be  extinguished 
before  they  arrive  at  it.  The  explosion  of  course  extinguishes  the 
flame,  but  when  the  plug  is  again  rotated  to  open  to  the  air,  the 
external  flame  relights  it  and  it  is  ready  for  another  ignition. 


FiO.  73.—  Harriett's  Igniting  Valve  (flame). 


Igniting  Arrangements  209 

Hugorfs  Igniting  Valve. — In  the  small  Hugon  engine  Barnett's 
method  was  first  applied  in  a  fairly  successful  manner. 

The  valve  is  shown  in  section  at  fig.  74. 

The  sectional  plan,  fig.  74,  shows  the  internal  flame  lit  and 
burning  in  the  ignition  port  i ;  the  external  flame  2  burns  close  to 
it  in  this  position,  so  as  to  be  ready  to  light  it  when  wanted.  The 
gas  for  the  internal  flame  is  supplied  under  higher  pressure  than 
that  of  the  ordinary  gas  mains  by  a  bellows  pump  and  small 
reservoir  through  the  flexible  rubber  pipe.  For  the  external  flame 
the  gas  is  used  at  the  ordinary  pressure. 

When  ignition  is  required,  the  valve  moves  rapidly  forward 
causing  the  port  i  to  close  to  atmosphere  first,  and  then  to  open 
to  the  cylinder  port  3,  as  shown  at  the  other  end  of  the  slide. 

The  explosive  mixture  which  fills  the  port  3  is  at  once 
ignited  and  the  flame  finds  its  way  from  the  port  into  the  cylinder 
itself  ;  the  port  is  necessarily  filled  with  pure  explosive  mixture 
free  from  any  admixture  with  exhaust  gases,  as  all  the  mixture 
before  entering  the  cylinder  must  pass  through  it  and  so  sweep 
before  it  any  burned  gases  into  the  cylinder.  Hence  the  mixture 
in  the  port  will  be  more  ignitable  than  that  in  the  cylinder,  as  the 
mixture  there  is  diluted  in  part  with  exhaust  gases  while  that  in 
the  port  is  free  from  them. 

The  explosion  is  thus  exceedingly  certain  and  regular  ;  when 
it  occurs  it  extinguishes  the  internal  flame  and  at  the  same  time  its 
superior  pressure  forces  back  the  gas  in  the  rubber  pipe  while  the 
port  i  remains  open  to  the  cylinder. 

The  return  of  the  slide  again  opens  it  to  the  atmosphere,  and  here 
is  seen  the  necessity  of  using  the  gas  under  some  pressure.  Before  it 
can  relight  at  the  external  flame,  the  products  of  combustion  must  be 
expelled  from  the  gas  pipe  ;  if  the  gas  were  under  only  the  ordinary 
gas  main  pressure  there  would  be  no  time  for  this,  and  the  valve 
would  return  to  ignite  without  a  flame.  The  expedient  of  increas- 
ing pressure  is  somewhat  clumsy  but  it  acts  fairly  well.  The  port  i 
is  made  large  to  give  space  for  the  air  necessary  to  support  the 
flame  while  the  ignition  port  is  passing  from  atmosphere  to 
cylinder  port.  At  the  moment  of  explosion,  the  cylinder  is  com- 
pletely closed  from  the  air. 

p 


The  Ga$  Engine 

The  explosion  is  therefore   completely  contained  within  the 
cylinder  and  no  sound  is  heard. 


§ 

£ 

•If 
1 


Igniting  A  rrangements  2 1 1 

In  the  engine  at  the  Patent  Office  Museum  Mr.  S.  Ford  con- 
siderably improved  the  igniting  arrangement  by  intercepting  the 
rush  back  to  the  gas  pipe  by  a  light  check  valve  ;  he  was  thus  able 
to  use  gas  under  the  ordinary  gas  main's  pressure  and  dispense 
entirely  with  Hugon's  gas  pump  and  reservoir.  The  explosion,  in- 
stead of  forcing  a  considerable  volume  of  burned  gases  down  the 
gas  pipe,  simply  closed  the  check  valve,  which  opened  as  soon  as 
the  igniting  port  reached  the  air  again,  and  so  gave  the  gas  stream 
at  once. 

Otto's  Igniting  Valve. — The  igniting  valve  used  in  the  Otto 
and  Langen  engines  is  a  further  development  of  Barnett  and 
Hugon's  igniting  devices. 

As  applied  to  the  compression  engine  there  is  one  alteration, 
very  slight,  but  very  essential. 

In  the  Lenoir  and  Hugon  engines,  as  well  as  the  Otto  and 
Langen,  the  pressure  in  the  cylinder  is  the  same,  or  in  some  cases 
less  than  that  of  the  external  atmosphere,  that  is,  before  ignition. 
It  is  therefore  an  easier  macter  to  transfer  a  flame  burning  quietly 
in  the  air  to  the  cylinder  without  danger  of  extinction.  When  the 
gases  to  which  the  flame  is  to  be  transferred  exist  at  a  pressure 
some  40  to  50  Ibs.  per  square  inch  superior  to  that  of  the  flame 
itself,  it  is  not  so  easily  seen  how  the  flame  is  to  be  transferred 
without  extinction.  Generally  described  the  arrangement  is  as 
follows.  A  small  quantity  of  coal  gas  is  introduced  into  the 
upper  part  of  a  cavity  in  the  ignition  slide  ;  being  lighter  than  air  it 
remains  separate  from  it  and  has  no  tendency  to  mix  with  the  air 
beneath  it,  except  by  the  slow  process  of  gaseous  diffusion.  At  the 
surface  of  contact. with  the  air,  it  is  ignited  and  burns  with  a  blue 
flickering  flame.  The  movement  of  the  slide  cuts  off  communica- 
tion with  the  outer  atmosphere,  and  very  shortly  thereafter  opens 
on  the  admission  port  of  the  engine,  but  before  doing  this  it  opens 
on  a  small  hole  communicating  with  the  cylinder.  This  hole  com- 
municates with  the  gas  passage  in  the  upper  part  of  the  slide,  so 
that  the  gases  under  pressure  enter  and  force  the  gas  downwards, 
the  pressure  rising  in  the  port  more  slowly  than  would  occur  if 
the  main  port  opened  at  once.  The  pressure  is  therefore  nearly 
level  with  that  in  the  cylinder  when  the  main  port  opens,  and  the 
flame  still  burning  at  the  point  or  surface  of  junction  between  the 

P  2 


212 


The  Gas  Engine 


gas  and  air,  ignites  the  mixture.  If  the  pressure  was  not  raised 
in  the  igniting  port  by  pressing  the  gas  downwards  and  thereby 
avoiding  a  rush  past  the  flame  portion,  the  rush  would  often 
extinguish  the  flame  and  an  ignition  would  be  missed.  The 
apparent  difficulty  of  transferring  the  flame  from  atmosphere  to 


FIG.  75. — Section,  Otto  Igniting  Valve. 

40  Ibs.  above  it  is  thus  simply  and  beautifully  overcome.  By  using 
a  portion  of  gas  in  the  upper  part  of  the  valve  cavity,  the  difficulty 
ot  the  blow  back  of  explosion  down  the  gas  supply  pipe  is  also 
overcome,  as  the  gas  supply  can  be  cut  off  before  the  explosion  or 


Ign  it  ing  A  rrangements  2 1 3 

compression  pressure  comes  on.  It  is  cut  off  just  before  the  valve 
closes  the  flame  port  to  atmosphere. 

Fig.  75  is  a  vertical  section  showing  the  flame  cavity  in  the  slide, 
in  the  act  of  introducing  coal  gas  at  the  upper  part  and  inflaming 
it  at  the  point  of  junction,  between  gas  and  air. 

The  slide  A  contains  a  forked  passage  B  communicating  at  the 
lower  passage  with  the  air  inlet  c,  and  at  the  upper  passage  with 
the  funnel  F,  which  are  both  in  the  valve  cover  D,  which  holds  the 
valve  against  the  engine  face,  The  jet  Q.  has  a  flame  constantly 
burning  into  the  funnel,  which  becomes  heated,  with  the  effect  of 
drawing  a  current  of  air  through  the  forked  passage  when  its  ports 
are  in  proper  position  ;  the  direction  of  the  current  is  shown  by 
the  arrows.  The  pipe  j  supplies  coal  gas  which  passes  along  the 
gutter  i,  cut  in  the  cover  and  valve  faces,  into  the  forked  passage 
c,  and  thence  to  the  funnel  F  where  it  is  inflamed  and  burns  as 
shown.  When  the  movement  of  the  slide  cuts  off  communication 
with  the  atmosphere,  it  also  closes  the  gutter  I  and  terminates  the 
supply  of  coal  gas  from  the  pipe  j,  but  the  upper  part  of  the  forked 
passage  contains  gas  ;  a  flame  therefore  flickers  as  shown.  Just 
before  B  opens  on  the  port  L,  fig.  76,  the  hole  K,  fig.  75,  opens  and 
the  pressure  from  the  explosion  space  causes  a  flow  into  B,  forcing 
before  it  the  gas  contained  in  the  hole,  thereby  intensifying  the 
flame  by  making  the  gas  pass  more  into  the  air  and  bringing  about 
the  equilibrium  of  the  pressures.  When  B  opens  on  L,  the  flame 
is  a  vigorous  one,  and  at  once  fires  the  whole  charge  in  the  explo- 
sion chamber.  Fig.  76  shows  the  slide  with  the  port  B  at  the 
moment  of  opening  on  L.  Fig.  77  is  an  end  elevation  of  the 
valve  and  cover,  showing  the  ports  and  gutters  dotted  and  lettered, 
position  same  as  in  fig.  76.  The  method  is  carried  out  completely 
and  is  a  very  perfect  one  indeed  ;  it  is  somewhat  slow  in  action, 
depending  as  it  does  on  a  proper  ventilation  of  the  forked  passage 
and  the  complete  replacement  of  the  burned  products  by  fresh  air 
before  the  gas  can  burn  properly  in  the  cavity.  If  the  engine  be 
run  more  rapidly  than  the  draught  6f  the  funnel  can  clear  out  the 
passage  from  the  burned  gases,  then  the  flame  cannot  be  lit  in  it 
and  an  ignition  will  be  missed. 

It  is  a  method  exceedingly  successful  when  ignition  is  not 
required  too  frequently,  but  very  troublesome  and  uncertain  for 


2I4 


The  Gas  Engine. 


rapid  ignition.     The  Otto  and  Langen  engine  only  made  30  igni- 
tions per  minute,  and  the  Otto  compression  engine  makes  but  80 


FIG.  76.— Sectional  Plan,  Otto  Igniting  Valve. 


Igniting  Arrangements 


215 


ignitions  per  minute  at  full  power  ;  its  efficiency  is  good  at  these 
rates,  but  at  150  per  minute  it  is  too  slow  in  action. 


Clerk's  Igniting  Valve. — The  method  of  igniting  the  charge  used 
by  Clerk  is  quite  different  from  the  other  flame  methods  already 
described  ;  the  difference  is  necessitated  by  the  greater  rapidity  of 
ignition  in  engines  with  an  impulse  for  every  revolution. 

To  ventilate  the  igniting  port  in  the  Otto  and  Hugon  slides 
requires  time,  which  cannot  be  given  when  the  frequency  of  the 
ignition  approaches  150  to  200  per  minute. 


2 1 6  The  Gas  Engine 

To  meet  this  difficulty  the  author  has  invented  several  methods 
both  flame  and  incandescence,  but  the  one  to  be  described  is 
that  at  present  in  use  in  his  engines  ;  it  is  very  reliable  and  rapid, 
as  many  as  300  ignitions  per  minute  having  been  made  with  it 
experimentally,  or  at  the  rate  of  5  ignitions  per  second. 

A  portion  of  the  explosive  charge  is  allowed  to  pass  from  the 
motor  cylinder  through  a  regulated  passage  to  a  grating  placed  at 
the  end  of  a  cavity  in  the  slide,  and  is  there  ignited  by  a  Bunsen 
flame  ;  the  grating  prevents  the  passage  back  of  the  flame,  and 
the  mixture  burns  in  the  cavity  without  requiring  the  presence  of 
the  external  atmosphere.  At  each  end  of  the  cavity  there  is  a 
port  opening  to  opposite  sides  of  the  valve,  the  one  for  lighting 
the  gases  streaming  from  the  grating,  the  othier  for  communicating 
with  the  interior  of  the  cylinder  at  the  proper  time.  The  com- 
munication with  the  cylinder  is  not  made  until  the  outer  port  cuts 
off  from  atmosphere,  and  the  flow  of  the  gases  is  so  regulated  that 
while  this  is  being  done,  the  flame  still  continues  to  be  fed  by 
fresh  supplies.  It  is  evident  that  if  too  great  a  current  be  sent  in, 
the  pressure  will  soon  become  equal  to  that  in  the  cylinder,  and 
then  the  flow  towards  the  cavity  will  cease  and  the  flame  become 
extinguished  ;  this  is  guarded  against  by  proper  proportioning  01 
the  blow  by  the  check  pin.  The  pressure  in  the  cavity  when  its 
port  opens  on  the  cylinder  port  is  still  slightly  less  than  that  in  the 
cylinder,  and  the  gases  from  the  cylinder  enter  and  are  ignited. 
By  using  gas  and  air  already  mixed  in  proper  proportion,  the  ne- 
cessity of  ventilating  is  removed,  and  it  is  made  possible  to  ignite 
at  the  rate  required  by  the  system  of  impulse  at  'every  revolution. 
Without  this  it  would  be  almost  impossible  to  get  a  passage  cleared 
out  in  time  to  allow  of  so  frequent  ignition,  by  a  coal  gas  flame 
burning  simply  in  air.  It  was  first  used  by  Clerk  in  an  engine  work- 
ing in  February  1878,  and  has  subsequently  been  used  by  Wittig 
and  Hees  and  by  Robinson  in  the  Tangye  engine.  In  the  form 
here  described  it  was  first  used  by  Clerk  in  November  1880. 

Fig.  78  is  a  sectional  plan  of  the  igniting  slide  and  cover  as 
well  as  the  passage  into  the  combustion  space.  The  valve  i  con- 
tains the  cavity  2,  furnished  at  the  ends  with  the  ports  3  and  4  ;  at 
the  end  3  is  placed  the  grating  5,  communicating  behind  with 
the  explosion  port  6,  by  a  small  hole  7  and  a  gutter  in  the 


Igniting  A  rrangements  2 1 7 

valve  face,  showing  at  fig.  78.  A  long  pin  8  screwed  into 
the  end  of  the  slide  controls  the  gases  entering  the  space  behind 
the  grating,  and  if  need  be  can  cut  off  communication  altogether. 
When  the  valve  is  in  the  position  shown  in  the  drawing,  the  mix- 


Valve  in  position  of  flame  lighting  at  external  flame. 
FIG.  78. —  Sectional  Plan,  Clerk  Igniting  Valve. 

ture  is  beginning  to  flow  through  the  grating  into  the  space  2, 
and  is  ignited  by  the  Bunsen  flame  9  lying  up  against  the  valve 
face.  The  Bunsen  flame  lies  so  close  to  the  grating  that  im- 
mediately inflammable  mixture  comes,  it  is  lighted  before  it  can 


218 


The  Gas  Engine 


get  time  to  fill  the  cavity  ;  if  allowed  to  accumulate  in  the  cavity 
before  lighting,  a  slight  explosion  ensues  and  a  disagreeable  report 
is  produced.  The  flame  at  the  grating  burns  in  the  cavity,  dis- 
charging into  the  passage  10,  and  from  thence  to  the  atmo- 
sphere. The  movement  of  the  slide  cuts  off  communication  with 
the  atmosphere,  first  on  the  Bunsen  flame  side,  and  then  on  the 


Internal  flame  exploding  mixture. 
FIG.  79.  —  Sectional  Plan,  Clerk  Igniting  Valve. 

inside  of  the  valve  ;  very  shortly  after,  the  port  4  opens  on  the  port 
6  leading  to  the  cylinder,  and  the  gases  then  taking  fire  communi- 
cate the  flame  to  the  whole  contents  of  the  compression  space. 
In  fig.  79  the  flame  port  in  the  valve  is  full  open  on  the  explosion 
port  of  the  engine.  The  slide  then  moves  past  the  port  and  back 


Igniting  Arrangements 


219 


xo  the  first  position,  where  the  operations  described  are  repeated 
and  igniting  again  occurs. 

This  arrangement  is  very  rapid  in  action,  and  is  capable  of 
igniting  with  the  utmost  regularity  at  a  rate  so  high  as  300  times 
per  minute,  which  is  far  in  excess  of  the  requirements  of  the 
engine.  Fig.  80  shows  the  Bunsen  flame  burning  against  the  face 
of  the  valve,  ready  to  ignite  the  gaseous  mixture. 


"JBUNSEM  BURNER 


FIG.  80.— End  Elevation,  Clerk  Igniting  Valve. 

Bray  ton's  Flame  Ignition.—  The  Brayton  method  of  ignition 
has  already  been  described  shortly  in  the  description  of  the  engine. 
It  is  so  beautiful  and  instructive  that  it  merits  further  discussion. 

The  action  will  be  made  clearer  by  describing  a  well-known 
laboratory  experiment  (fig.  81). 

A  piece  of  wire  gauze,  a,  held  a  few  inches  from  the  Bunsen 
lamp,  />,  the  gas  being  turned  on,  will  prevent  the  flame  when  lit 


220 


The  Gas  Engine 


above  it  from  passing  back  through  the  gauze  to  the  burner.  The 
gauze  may  be  moved  through  a  considerable  distance  from  the 
Bunsen  tube  without  extinguishing  the  flame.  The  mixture  of  gas 
and  air  streaming  from  the  Bunsen  passes  through  the  gauze,  and, 
although  igniting  above,  the  heat  is  so  rapidly  conducted  away  by 
the  gauze,  that  the  flame  cannot  pass  through  its  interstices  back 
to  the  lower  side.  If  an  explosive  mixture  be  confined  under  say 
30  Ibs.  per  square  inch  pressure  in  a  vessel,  and  a  pipe  from  it 
(fig.  82)  leads  to  a  pair  of  perforated  plates  with  gauze  between 
them,  a,  then  the  cock  b  being  opened  gently  (the  valve  c  being 
previously  open),  the  mixture  will  stream  through  the  plates  into 


FIG.  81.  —  Bunsen  Flame  burning  above  Gauze. 

the  atmosphere,  and,  if  ignited,  will  burn  at  a  without  passing 
back.  If  the  cock  b  is  opened  suddenly  a  greater  rush  of  flame 
will  occur,  diminishing  again  if  it  is  partly  closed. 

So  long  as  enough  mixture  passes  to  preserve  alive  the  flame 
at  a,  then  any  increased  quantity  passing  from  the  reservoir  will 
be  burned  ;  the  little  flame  increasing  or  diminishing  as  the 
opening  of  the  stop-cock  valve  is  increased  or  diminished. 

The  action  of  the  ignition  in  the  Brayton  engine  is  exactly 
similar.  The  pressure  on  the  flame  side  of  the  grating  is  slightly 
below  that  existing  on  the  ether  side  j  the  stream  of  cold  gases 


Igniting  Arrangements 


221 


entering  the  engine  cylinder  immediately  becomes  flame  on  the 
grating,  and  so  expands,  the  volume  of  flame  being  changed  as 
required  by  the  valve  action  of  the  engine. 

This  method  is  most  successfully  carried  out  in  the  Brayton 
engine.  The  lack  of  economy  is  not  due  to  the  ignition,  but  to 
the  use  of  it  under  unsuitable  circumstances.  Without  doubt  this 


Plan  of  grating. 
FIG.  82.— Brayton  Grating  and  Valve. 

system,  in  a  better  combination,  will  come  largely  into  use  in 
future  and  larger  gas  engines.  It  is  unsuited  for  cold  cylinder 
explosion  engines,  but  admirably  adapted  for  hot  cylinder  com- 
bustion engines  of  the  second  type. 


222 


The  Gas  Engine 


(3)  INCANDESCENCE  METHODS. 

The  ignition  of  explosive  mixtures  by  contact  with  heated 
metallic  surfaces  has  often  been  proposed,  first  by  the  late  Sir 
C.  W.  Siemens,  and  after  him  by  the  American,  Drake.  Dr. 
Siemens,  in  one  of  his  gas  engine  patents,  proposes  to  ignite  the 


FIG.  83.— Sectional  Plan,  Clerk  Incandescent  Platinum  Igniting  Valve. 

mixture  by  passing  it  through  an  iron  tube,  which  is  heated  to  red- 
ness by  a  flame  outside  of  it. 

Drake  constructed  an  engine  in  which  the  ignition  was  effected 
in  a  similar  manner.     The  difficulty  is  found  in  the  rapid  oxidation 


Igniting  A  rrangements  223 

of  the  tube,  and  the  consequent  necessity  for  frequent  renewal. 
Frequent  attempts  have  also  been  made  to  heat  a  portion  of  the 
interior  surface  of  the  cylinder,  so  that  at  a  suitable  time  the  mix- 
ture might  be  exposed  to  it  and  fired. 

The  first  arrangement  of  incandescent  ignition  successfully 
applied  to  a  compression  engine  is  the  invention  of  the  author, 
and  is  described  in  his  patent,  No.  3045,  1878.  It  was  used  in  an 
engine  exhibited  at  the  Royal  Agricultural  Society's  Show,  Kilburn, 
in  1879  (July). 

Clerk's  Igniting  Valve. — Fig.  83  is  a  sectional  plan  of  this 
valve  in  position.  Fig.  84  is  a  separate  view  of  the  valve  looking 
upon  the  face,  and  fig.  85  is  the  platinum  cage,  full  size,  taken  out 
of  the  valve. 


me 
p 


FIG.  84.  — Face  of  Valve  with  Platinum  Cage. 


FIG.  85.— Platinum  Cage. 

The  platinum  cage  consists  of  a  box  of  platinum  plate,  with 
numerous  platinum  ribs  running  across  it.  They  are  secured  by 
rivets  running  completely  through,  small  platinum  washers  serving 
to  keep  the  plates  at  equal  distances.  The  valve  receives  this 
cage  in  a  cavity,  and  it  is  tightly  packed  in  its  place  with  asbestos 
and  slate  packing,  a  covering  plate  screwed  down  upon  it  securing 
the  whole  in  position.  To  start  the  engine,  the  reservoir  contain- 
ing gas  and  air  under  pressure  is  opened  ;  the  small  tap,  i,  then 
opened  allows  mixture  to  flow  through  the  diaphragm  2  (made 
like  the  Brayton  grating),  and  the  mixture  is  ignited  at  the 
small  door  3,  which  is  then  closed.  The  flame  flows  through  the 


224 


The  Gas  Engine 


platinum  cage,  heating  up  its  plates  to  a  white  heat  in  a  few 
seconds.  On  opening  the  starting  cock  of  the  engine,  it  moves, 
and  brings  the  igniting  port  4,  on  the  cylinder  port  5,  at  the  same 
time  opening  on  the  port  6,  in  the  cover,  leading  into  the  cavity  7. 
The  mixture  in  the  cylinder  then  rushes  through  the  cage,  becom- 
ing ignited,  and  the  explosion  reaches  the  cylinder  ;  the  cavity  7 

is  so  proportioned  that  each  igni- 
tion sends  a  measured  quantity 
of  flame  through  the  cage  into  it  ; 
the  heat  of  the  explosion  at  every 
turn  therefore  supplies  heat  to 
the  platinum.  This  added  heat 
is  sufficient  to  keep  it  at  a  white 
heat.  So  long  as  the  engine  is 
supplied  with  gas  it  gets  an  ig- 
nition at  every  revolution,  and  a 
portion  of  that  heat  goes  to  the 
platinum  to  make  up  for  loss  by 
conduction.  The  heating  flame 
used  in  starting  the  engine  is 
dispensed  with  immediately  on 
starting,  and  the  engine  runs  con- 
tinuously without  outside  flame. 
This  method  is  exceedingly  reli- 
able and  rapid,  but  is  not  suited 
for  the  governing  arrangements 
of  small  engines. 

Siemens'  Tube  Method. — Fig.  86 
is  an  arrangement  of  Siemens' 
method,  as  used  by  Mr.  Atkinson 
in  his  '  Differential '  engine,  ex- 
hibited at  the  Inventions  Exhibi- 
tion. The  wrought  iron  tube  i  is 
FIG.  86.— Hot  Tube  Igniter.  heated  by  the  Bunsen  flame  2, 

the  non-conducting  casing  3  pre- 
venting loss  of  heat ;  the  piston  at  the  proper  time  uncovers  the 
hole  4  into  which  the  tube  is  screwed,  and  the  mixture  entering 
under  pressure  becomes  ignited.  In  other  engines  the  tube  is 


Ign iting  A  rrangements  225 

caused  to  communicate  with  the  cylinder  by  a  valve.  This  modi- 
fication is  exceedingly  simple  and  works  well ;  care  must  be  taken 
to  avoid  overheating,  or  the  explosion  may  rupture  the  tube.  It 
is  inexpensive  and  easily  renewed  when  disabled  by  oxidation. 

(4)  METHODS  DEPENDING  ON  CATALYTIC  AND 
CHEMICAL  ACTION. 

The  well-known  property  of  spongy  platinum  of  causing  the 
spontaneous  ignition  of  a  stream  of  hydrogen  or  coal  gas  directed 
on  it  in  air,  has  been  proposed  as  a  means  of  ignition  by  Barnett 
(1838).  In  the  arrangement  he  describes,  the  platinum  is  contained 
in  a  little  cup  screwed  into  the  cylinder  cover,  and  the  compression 
of  the  mixture  causes  its  ignition  by  contact. 

Platinum,  however,  soon  loses  this  property,  and  the  action  is 
at  best  too  slow  for  use. 

All  flame  methods  of  course  depend  on  chemical  action,  but 
one  proposal  has  been  made,  to  use  the  property  possessed  by 
phosphorated  hydrogen  of  igniting  spontaneously  in  contact  with 
air.  The  phosphorated  hydrogen  is  conducted  in  small  quantity 
into  the  mixture  to  be  exploded  at  every  revolution,  and  its  com- 
bustion causes  ignition. 

This  proposal  has  never  been  carried  out  in  practice. 

Summary. — To  the  author's  knowledge  no  other  systems 
of  ignition  have  been  proposed  ;  the  flame  methods  are  best 
suited  for  small  gas  engines  and  will  probably  continue  in  use. 
Considerable  improvements  may  still  be  effected  in  ignition  valves, 
and  it  is  possible  that  external  flames  may  be  entirely  done 
away  with  in  future  engines.  It  is  somewhat  humiliating  to  the 
inventor  to  watch  a  powerful  gas  engine  at  work,  developing  say 
30  horses,  and  to  know  that  he  can  at  once  change  the  whole 
and  make  the  engine  powerless  by  blowing  out  the  external  flame. 

A  combination  of  flame  and  incandescence  methods  will  doubt- 
less overcome  this  difficulty,  and  make  the  gas  engine  act  without 
visible  flame  and  without  the  danger  of  extinction  from  diaught, 
to  which  the  present  igniting  flames  are  subject. 

It  is  improbable  that  either  the  first  or  fourth  methods  will 
again  find  favour,  the  electric  methods  give  too  much  trouble  and 
are  at  best  uncertain. 

Q 


226  The  Gas  Engine 


CHAPTER   IX. 

ON    SOME   OTHER    MECHANICAL    DETAILS. 

A  GOOD  working  cycle  and  good  igniting  arrangements  are  the  two 
most  important  factors  in  the  successful  working  of  a  gas  engine, 
but  there  are  other  matters  whose  importance  is  only  secondary 
to  those.  The  governing  gear,  the  oiling  gear,  and  the  starting 
gear,  are  of  the  greatest  importance. 

These  matters  will  now  be  described. 

The  Governing  Gear. — In  the  earlier  gas  engines,  including 
Lenoir  and  Hugon,  the  governing  was  attempted  precisely  as  is 
done  in  the  steam  engine,  the  source  of  power  being  regulated 
by  throttling.  A  centrifugal  governor  acted  upon  a  throttle  valve 
regulating  the  gas  supply,  diminishing  it  when  the  speed  became 
too  great  and  increasing  it  when  the  speed  fell. 

This  was  a  very  bad  and  wasteful  method,  as  the  engineer  will 
at  once  recognise  from  his  knowledge  of  the  properties  of  explosive 
mixtures. 

The  limits  of  change  allowable  in  the  proportions  of  gaseous 
explosive  mixtures  are  very  narrow,  the  gas  present  ranging  from 
\  to  TV  of  the  total  volume.  A  mixture  containing  |  of  its  volume 
of  coal  gas  in  air  has  just  sufficient  oxygen  to  burn  it  and  no 
more  ;  any  further  increase  of  gas  will  pass  away  unburned,  there 
being  insufficient  oxygen  present  for  its  combustion. 

This  is  therefore  the  richest  mixture  which  can  be  used  with 
any  economy. 

A  mixture  of  air  and  gas  containing  T\r  of  its  volume  of  gas  is 
in  the  critical  proportion  ;  any  further  dilution,  however  slight,  will 
cause  it  to  lose  inflammability  altogether.  The  governor  may 
act  in  changing  the  proportion  of  gas  and  air  between  those  limits, 
that  is,  the  explosion  may  be  so  reduced  by  dilution  that  it  gives 


On  some  other  Mechanical  Details 


227 


only  naif  the  power  per  impulse  obtainable  with   the  strongest 
mixture. 

Any  further  dilution  causes  the  engine  to  miss  ignition  al- 
together, and  discharge  the  gas  it  has  taken  into  the  exhaust  pipe, 
without  obtaining  any  power  from  it.  If,  therefore,  the  governor 
acts  by  throttling,  the  valve  is  only  closed  enough  to  cause  the 
mixture  to  be  so  weak  as  to  miss  fire ;  as  soon  as  that  point  is 
reached  the  valve  will  be  closed  no  further,  because  at  that  point 
the  speed  of  the  engine  will  cease  to  increase.  Fig.  7,  p.  14,  shows 
the  governor  in  action  upon  a  Lenoir  engine. 


FIG.  87. — Section  showing  Otto  and  Langen  Governor. 

In  modern  compression  engines  the  great  loss  of  gas  occasioned 
by  throttling  is  avoided  by  never  diluting  the  mixture.  Instead  of 
keeping  up  the  same  frequency  of  impulses  but  of  less  power,  as 
done  in  the  steam  engine,  the  gas  is  either  full  on  or  full  off, 
that  is,  the  governing  is  effected  by  diminishing  the  frequency  of 
the  impulses  instead  of  diminishing  their  power. 

In  the  specification  of  the  Otto  engine,  1876  (2081)  the 
governing  is  described  as  being  effected  by  reducing  the  power 
of  the  explosion.  This  is  more  impracticable  in  the  Otto  engine 

Q  2 


228 


The  Gas  Engine 


than  in  the  Lenoir,  because,  owing  to  the  dilution  of  the  charge  by 
the  exhaust  gases  or  air,  the  range  of  change  in  mixture  is  smaller. 
The  strongest  mixture  does  not  exceed  i  of  coal  gas  in  8  of  other 
gases. 

Governing— Otto  and  Langen  Engine.— In  this  engine,  in  its 
latest  and  best  form,  the  governing  is  effected  by  missing  impulses. 
When  the  engine  has  received  an  impulse,  the  increase  in  speed 
causes  the  governor  to  move  a  lever  which  disengages  a  pawl  from 
a  ratchet,  and  so  prevents  the  piston  being  raised  and  the  charge 
drawn  into  the  cylinder.  When  the  speed  has  fallen  sufficiently 


FIG.  88.— Otto  and  Langen  Governor,  showing  Pawl  and  Ratchet. 

the  lever  liberates  the  pawl,  and  the  piston  is  then  raised,  taking 
in  the  charge  and  exploding  it.  Fig.  87  is  a  sectional  elevation  of 
the  governing  arrangements.  The  auxiliary  shaft  i  is  driven  from 
the  main  shaft  2  by  the  clutch  3,  but  the  crank  4  and  shaft  i  re- 
ceive motion  from  2  only  by  means  of  the  pawl  5  falling  into  the 
ratchet  3  ;  so  long  as  the  governor  lever  7  remains  in  the  position 
shown,  the  pawl  is  kept  from  engaging  and  the  piston  and  valve 
remain  at  rest ;  so  soon  as  the  governor  lever  7  liberates 
the  pawl,  then  it  falls  into  the  ratchet  wheel  by  a  spring  and  the 


On  some  other  Mechanical  Details 


229 


auxiliary  shaft  receives  one  turn  ;  the  crank  4,  connected  to  the 
lever  8  (fig.  88),  lifts  the  rack,  and  the  piston  takes  in  its  charge  ; 
at  the  same  time  the  valve  opens  to  gas  and  air,  then,  when 
the  piston  is  full  up,  brings  on  the  igniting  flame.  The  ex- 
plosion occurs  and  shoots  up  the  piston,  which  on  its  down  stroke 
accelerates  the  motion  of  the  power  shaft,  and  if  the  limit  of  speed 
is  exceeded,  the  governor  lever  again  interposes  and  prevents  the 
charge  and  explosion  till  the  speed  falls. 

When  running  without  any  load,  the  two  horse  engine  tested 
at  Manchester  by  Clerk  required  only  6  ignitions  per  minute,  con- 
suming, including  side  lights,  about  25  cubic  feet  per  hour.  The 
shaft  therefore  ran  as  many  as  1 5  revolutions  merely  by  the  power 
stored  in  the  fly-wheels. 

The  governing  is  effective  but  irregular. 

Governing — Otto  Engine. — The  speed  of  the  Otto  compression 
engine  is  governed  by  diminishing  the  number  of  impulses  given 
to  the  crank  ;  whenever  the  normal  rate  is  exceeded,  the  governor 
so  acts  that  the  gas  supply  is  completely  cut  off  for  one  or  more 
strokes  of  the  engine,  no  impulse  being  given  till  it  falls  again. 

One  arrangement  very  commonly  in  use  is  shown  at  fig.  89. 

The  cam  i  upon  the  auxiliary  shaft  2  is  arranged  to  strike  the 
wheel  3  upon  the  lever  4,  opening  the  gas  valve  5  at  the  begin- 
ning cf  the  stroke  and  keeping  it  open  till  the  end  of  the  stroke 
of  the  piston;  the  gas  passes  from  the  gas  valve  by  a  passage  to  the 
holes  in  the  slide,  when  it  streams  into  the  air  current  entering  the 
engine  by  the  admission  port.  Whenever  the  speed  becomes  high 
enough,  the  governor  6  by  the  lever  7  shifts  the  position  of  the  cam 
i  upon  its  shaft,  so  that  the  wheel  3  does  not  strike  it;  the  gas  valve 
5  therefore  remains  shut  for  that  stroke,  and  the  piston  draws  air 
alone  into  the  cylinder.  When  the  piston  returns  and  compresses 
the  charge,  the  igniting  flame  enters  as  usual,  but  there  being 
no  explosive  mixture  there,  the  piston  moves  out  again  without 
impulse,  expanding  and  discharging,  charging  and  compressing  an 
uninflammable  charge,  till  the  reduction  of  speed  calls  again  for  an 
impulse  ;  the  first  ignition  after  the  engine  has  made  several  re- 
volutions without  gas  is  always  more  powerful  than  the  normal 
one,  because  no  exhaust  gases  being  there  the  charge  mixes  in  the 
space  with  pure  air  and  is  not  heated  previous  to  explosion. 


230 


The  Gas  Engine 


The  arrangement  in  different  Otto  engines  varies  from  this,  but 
the  principle  is  always  the  same. 

Fig.  90  is  a  recent  and  very  clever  governing  arrangement  as 
used  in  the  smaller  Otto  engines. 


FIG.  89.— Otto  Governor  and  Connecting  Gear. 

The  ordinary  governor  is  entirely  dispensed  with,  and  the  valve 
itself  carries  a  pendulum  which  governs. 

The  pendulum  i,  hanging  from  the  pin  2  in  the  slide  valve  3, 
carries  the  long  steel  blade  4,  which  usually  strikes  the  stem  5,  and 
opens  the  gas  valve  at  the  same  time  as  the  slide  opens  to  the  air. 
Whenever  the  speed  is  exceeded,  however,  the  motion  of  the  valve 


i 


On  some  other  Mechanical  Details  23  f 

in  the  direction  of  the  arrow,  exceeding  a  certain  rate,  the  pendu- 
lum i  is  left  behind  and  depresses  the  steel  blade  4,  which  therefore 
misses  the  gas  valve  stem  and  for  that  revolution  no  gas  enters. 
So  long  as  the  speed  is  sufficient  to  swing  back  the  pendulum  no 
gas  enters  ;  as  soon  as  it  is  insufficient  to  cause  the  pendulum  to 
leave  its  resting  position  against  the  valve,  then  gas  is  admitted. 

As  the  pressure  of  the  edge  of  the  steel  plate  upon  the  valve 
stem  is  in  direct  line  with  the  centre  of  the  pin  upon  which  the 
pendulum  hangs,  there  is  no  tendency  to  move  it,  that  is,  the 
governor  does  not  furnish  the  power  to  open  the  gas  valve.  In 
all  the  Otto  governing  arrangements  this  principle  is  adhered  to ;  the 


FIG.  90. — Otto  Pendulum  Governor. 

governor  never  furnishes  the  power  to  move  the  gas  valve,  but 
only  signals  to  the  engine  the  proper  time  to  give  the  motion, 
the  motion  being  always  taken  from  the  engine  itself. 

In  electric  light  engines,  which  must  give  the  impulse  for  every 
two  revolutions  with  some  change  of  power,  the  gear  is  modified  ; 
instead  of  complete  cut-off  as  first  described,  the  cam  upon  the 
shaft  is  made  in  several  steps,  so  that  the  wheel  upon  the  gas  lever 
is  shifted  from  one  to  another  as  shown  in  fig.  91,  where  i  is  the 
gas  cam,  and  2  is  the  wheel  upon  the  gas  lever.  Those  steps  are 
made  to  diminish  supply  of  gas  as  much  as  possible  without  miss- 
ing ignition,  so  that  within  narrow  limits  of  changing  load,  the 


232 


The  Gas  Engine 


engine  may  retain  its  frequency  of  impulse.  Whenever  this 
range  of  permissible  variation  is  exceeded,  the  wheel  slips  entirely 
off  the  cam,  and  the  engine  then  governs  in  the  ordinary  manner. 


FIG.  91.— Otto  Electric  Light  Governor. 

Governing — Brayton  and  Simon. — In  the  Brayton  gas  engine 
the  governing  was  effected  precisely  as  in  the  best  steam  engine?, 
by  varying  the  point  of  cut-off.  The  entering  flame  was  cut  off, 
sooner  or  later,  as  determined  by  the  governor  of  the  engine  ;  and 
the  admission  of  gas  and  air  to  the  pump  was  simultaneously 
regulated,  the  amount  entering  being  diminished  to  keep  the 
pressure  in  the  reservoir  constant.  The  diagram,  fig.  45,  p.  158, 
shows  that  the  variable  cut-off  acted  well. 

Fig.  92  shows  the  governor  of  the  petroleum  engine. 

The  cam  i,  which  opens  the  admission  air  valve  on  the  motor 
cylinder,  is  made  tapering,  so  that  the  point  of  cut-off  becomes 
earlier  and  earlier  as  it  slides  in  the  direction  of  the  arrow. 

The  supply  cf  air  was  thus  diminished.  In  this  engine  the 
supply  of  petroleum  could  only  be  diminished  by  hand,  two  screws 
on  the  oil  pump,  when  screwed  upwards,  altering  the  connecting 


On  some  other  Mechanical  Details 


233 


rod  between  the  plunger  and  the  eccentric,  giving  more  or  less 
iree  movement,  and  thereby  diminishing  the  throw  of  the  pump. 

The  air  supply  to  the  engine  was  not  diminished,  so  that  the 
pressure  in  the  reservoir  increased,  and  was  blown  off  at  a  safety 
valve  placed  upon  the  engine.  This  was  a  wasteful  method. 

The  regularity  of  this  engine  in  running  was  very  great,  being 
far  superior  to  any  of  the  modern  compression  engines.  It  was, 
however,  not  at  all  economical. 

Simon's  engine  presented  no  new  feature  in  its  governing 
arrangements.  They  were  quite  similar  to  Brayton. 


FIG.  92. — Brayton  Governor. 

Governing— Clerk  Engine. — The  governing  gear  now  used 
upon  this  engine  is  the  design  of  Mr.  G.  H.  Garrett,  Messrs. 
L.  Sterne  &  Co.'s  works'  manager.  It  is  shown  at  figs.  93  and  94. 

It  consists  of  a  gridiron  slide  placed  between  the  upper  and 
lower  lift  valves.  So  long  as  the  engine  is  at  full  power,  the  slide 
i,  fig.  93,  is  moved  by  the  lever  2,  fig.  94,  from  the  ignition  slide 
of  the  engine  already  described,  and  remains  open  during  the 
forward  stroke  of  the  displacer  piston. 

The  charge  of  gas  and  air  therefore  enters  during  the  whole 
stroke,  and  is  sent  into  the  motor  cylinder  to  be  compressed  and 
ignited  at  the  proper  moment.  If,  however,  the  load  is  lessened, 
and  the  speed  increases,  and  the  governor  3  acts,  it  moves  the 
lever  4,  which  then  catches  the  lever  2,  and  prevents  the  spring  5 
from  taking  the  slide  i  back  and  opening  it.  The  displacer  then 
discharges  its  contents  into  the  motor  cylinder,  but  on  its  next 
out-stroke,  the  valve  i  being  closed,  it  gets  no  charge  but  the 


234 


The  Gas  Engine 


o 


FIG.  93.— Sections  and  Plan,  Governor  Slide,  Clerk  Engine. 


FIG.  94.  — Clerk  Engine  showing  Garrett  Governor  Gear. 


On  some  other  Mechanical  Details 


235 


piston  moves  out,  forming  a  partial  vacuum  behind  it.  The  motor 
cylinder,  therefore,  receives  no  charge  from  the  displacer  cylinder, 
and  the  motor  piston  compresses  and  expands  alternately  the 
burned  gases  behind  it,  while  the  displacer  piston  moves  out  and 
in,  expanding  and  compressing  likewise.  This  goes  on  till  the 
governor  signals  reduction  of  speed,  and  disengages  the  lever  2, 
by  pushing  down  the  lever  4,  so  that  the  spring  5  opens  the  slide 
i,  and  the  engine  gets  a  charge. 

This  method  works  very  well  and  economically  ;  it  is  necessi 
tated   by  the   clearance  space  unavoidable  in  the  Clerk  engine 
between  the  motor  and  displacer  cylinders.     If  gas  were  cut  off  as 
in  the  Otto,  that  space  filled  with  mixture  would  be  lost  every  time 
the  governor  acted. 

Governing — Tangye  Engine. — Messrs.  Tangye's  gas  engine  is 
now  controlled  by  a  very  ingenious  governor,  the  invention  of 


FIG.  95.— Governing— Tangye  Engine. 

Mr.  C.  W.  Pinkney.  It  is  shown  at  fig  95.  The  rod  i  i,  moved 
to  and  fro  by  an  eccentric,  carries  with  it  the  bracket  2,  into 
which  is  fixed  the  pin  3  ;  on  this  pin  the  lever  4  is  swung,  and 
moves  to  and  fro  with  the  bracket ;  the  lever  is  pressed  gently 
downwards  by  the  spring  5,  and  the  lower  part  of  the  lever  is 
formed  into  an  incline  at  6,  so  that  as  it  moves  the  spring  presses 
it  against  the  roller  7.  So  long  as  the  engine  does  not  exceed  its 
proper  speed,  the  lever  4  does  not  rise  above  the  position  shown 


236  The  Gas  Engine 

in  the  figure  when  it  is  moving  in  the  direction  of  the  arrow,  and 
accordingly  its  knife  edge  end  strikes  the  lever  8  and,  acting 
through  the  intermediate  links,  opens  the  gas  valve  9.  The 
engine  gets  its  charge  of  gas  every  time  the  gas  valve  opens.  If 
/he  speed  becomes  too  great,  then  the  upward  velocity  given  to 
the  lever  4  by  the  stationary  roller  7  forcing  against  the  incline  is 
such  that  the  knife  edge  lever  4  rises  above  the  end  of  the  lever 
8,  and  the  gas  valve  remains  closed.  When  the  speed  falls 
sufficiently  the  lever  4  again  strikes  the  lever  8  and  opens  the  gas 
valve. 

The  incline  governor  works  well  and  is  exceedingly  sensitive 
to  change  in  speed  :  by  altering  the  compression  upon  the  spring 
5  the  speed  of  the  engine  can  be  varied. 

Oiling  Gear. — In  the  steam  engine  the  comparatively  low 
temperature  of  the  steam  within  the  working  cylinder  and  the 
fact  of  its  condensation  upon  the  walls  and  piston  renders  the 
task  of  lubricating  an  easy  one.  The  lubrication  need  not  be 
absolutely  continuous  and  the  nature  of  the  oil  may  vary  much 
and  no  harm  is  done. 

With  the  gas  engine,  the  intense  flame  filling  the  cylinder  at 
every  stroke  quickly  destroys  the  film  of  oil  with  which  it  is 
covered,  and  necessitates  its  continuous  renewal. 

If  animal  oil  be  used,  its  decomposition  leaves  considerable 
charred  matter,  which  speedily  coats  the  piston  and  cylinder, 
causing  friction  and  danger  of  cutting.  A  good  hydrocarbon,  on 
the  other  hand,  even  when  subjected  to  intense  heat,  decomposes 
into  gases  without  leaving  any  appreciable  amount  of  carbon  : 
mineral  oils  should  therefore  alone  be  used  for  the  cylinder  and 
ignition  slide. 

The  amount  of  oil  required  for  these  parts  is  small  per  day, 
but  it  must  be  regularly  applied  ;  the  burned  film  removed  from 
the  surface  of  the  cylinder  at  every  explosion  must  be  regularly 
replaced  or  abrasion  of  the  surfaces  would  speedily  ensue. 

In  the  Otto  engine  the  oil  required  is  supplied  during  the  whole 
action  of  the  engine  ;  it  commences  with  the  movement  of  the  en- 
gine, continues  so  long  as  it  is  running,  and  stops  when  motion  ceases. 

Fig.  96  shows  the  Otto  oiling  cup,  one  of  which  is  placed,  as 
shown  in  the  draw'ng,  fig.  97,  at  the  middle  of  the  cylinder  to 


On  some  other  Mechanical  Details 


237 


lubricate  the  piston  and  slide  ;  the  pipes  4  and  5  lead  to  the 
piston  and  slide. 

The  pulley  i  is  driven  slowly  from  the  auxiliary  shaft  by  a 
strap,  and  as  it  rotates  it  carries  the  wire  2  round  on  the  pin  3, 


FIG.  96.— Illustration  of  action  of  Otto  Oiler. 

fig.  96,  alternately  dipping  into  the  oil  and  wiping  it  off  to  the 
pin,  from  whence  it  drops  into  the  trough  4  and  runs  by  a  hole 
into  the  tubes.  The  amount  of  oil  so  discharged  can  be  regulated 
by  the  diameter  of  the  wire.  The  oil  flows  along  the  pipes  4  and 


FIG.  97. — Arrangement  of  Otto  Oiler. 

5,  fig.  97,  and  drops  into  holes  at  6  and  7,  the  one  oiling  the  piston 
every  time  the  trunk  comes  forward,  the  other  oiling  the  valve  by 
suitable  gutters. 

The  Clerk  oiling  cup  is  shown  at  fig.  98  ;  it  is  not  automatic. 
The  screw  pin   i  is  set  in  a  position  marked  for  each  cup,  the 


The  Gas  Engine 

motor  cylinder  cup  giving  15  drops  per  minute,  and  the  valve  cup 
5  drops  per  minute. 

In  both  Otto  and  Clerk  engines  the  slide  valves  should  be 
taken  out  and  cleaned  once  a  week.  The  charred  oil  should  be 
carefully  scraped  out  of  the  gas  gutters  and  igniting  ports  ;  the 
piston  also  should  be  drawn  occasionally,  once  in  three  months 
being  sufficient.  The  interior  of  the  cylinder  should  then  be 
cleaned,  especially  the  explosion  space.  The  Otto  exhaust  valve 
should  be  taken  out  every  week  and  cleaned.  The  Clerk  upper 


FIG.  98. -Clerk  Oil  Cup. 

and  lower  lift  valves  require  cleaning  once  every  month  if  the 
engine  is  hard  worked. 

In  working  gas  engines  the  two  points  requiring  attention  are 
oiling  and  cleaning.  Never  run  the  engine,  without  oil,  and  clean 
regularly.  Never  start  without  seeing  that  the  water  circulation 
is  open. 

Starting  Gear. — Till  very  lately,  gas  engines  of  every  power 
were  started  by  manual  labour  ;  in  small  machines  the  inconveni- 
ence is  not  great,  but  with  large  engines  such  as  those  giving 
from  20  to  50  indicated  horses  when  at  full  power,  the  friction 
is  so  considerable  that  difficulties  arise.  It  is  difficult  to  reduce 
friction  so  much  that  a  large  machine  may  be  turned  with  suffi- 
cient velocity  by  a  couple  of  men,  to  get  a  sure  and  easy  start. 

The  Brayton  petroleum  engine  was  the  first  to  use  reservoirs 


On  some  other  Mechanical  Details 


239 


for  retaining  sufficient  air  for  starting,  but  they  were  so  faultily 
constructed,  that  leakage  and  loss  were  so  frequent  that  the  appa- 
ratus was  of  little  use.  Many  arrangements  have  been  described 
by  inventors,  but  no  starting  gear  found  its  way  into  public  use 
till  that  invented  by  the  present  author  in  the  end  of  1883.  The 
Clerk  engine  was  the  first  to  use  starting  gear  in  public,  at  the 


FIG.  99. — Clerk  Starting  Gear. 

beginning  of  1884.  Since  then  over  100  engines  have  been  fitted 
and  are  at  daily  work  with  it. 

The  Otto  engine  speedily  followed  Clerk's  in  the  application 
of  gear,  and  after  them  came  Tangye  and  Atkinson. 

Starting  Gear — Clerk  Engine. — The  starting  gear  used  in  the 
Clerk  engine  is  shown  at  figs.  99  and  100.  Its  action  is  as  follows. 


240 


The  Gas  Engine 


The  flap,  valve  i,  in  the  communicating  pipe  between  the  displacer 
and  motor  cylinders  is  closed,  while  the  engine  is  running,  by  the 
handle  2  ;  the  gases  in  the  displacer  are  thus  prevented  from 
entering  the  motor  cylinder,  and  are  compressed  through  the 
valve  3,  which  is  an  automatic  lift,  into  the  reservoir  4,  by  the  stop- 
valve  5,  which  must  of  course  be  open. 

The  ignition  being  stopped,  the  speed  of  the  engine  falls,  and 
the  flap  is  opened  for  a  few  strokes,  to  allow  the  speed  to  get  up 
again.  It  is  then  closed  again,  this  being  repeated  till  the  reservoir 
4  is  charged  with  a  mixture  of  gas  and  air  at  60  Ibs.  per  sq.  in. 
above  atmosphere.  Five  minutes  gives  ample  time  to  charge 


FIG.  IOO.— Clerk  Starting  Valve. 

from  completely  empty  to  60  Ibs.  Three  minutes  suffice  if  the 
charge  has  not  been  completely  taken  from  the  reservoir  during 
the  previous  start.  The  relief  valve  at  6  prevents  charging  above 
60  Ibs.  per  sq.  in.,  the  excess  blowing  into  the  exhaust  pipe. 
When  the  reservoir  is  charged  the  stop  valve  5  is  screwed  down 
and  the  charge  is  retained  in  the  reservoir  till  wanted.  The 
reservoir  is  made  of  steel,  the  sides  being  \  in.  thick  and  the  ends 
f  ;  it  is  welded  throughout,  and  is  tested  before  leaving  the  works 
at  1000  Ibs.  per  sq.  in. 

The  screw  down  valve  5  and  the  joint  where   it  is  screwed 


On  some  other  Mechanical  Details 


241 


into  the  end  form  the  only  joints  for  loss  by  leakage  ;  numerous 
joints  must  be  avoided,  as  it  is  often  necessary  to  leave  the 
reservoir  charged  for  weeks  ;  the  faintest  leakage  would  in  so  long 
a  time  lose  the  contents,  and  so  the  start  would  require  to  be 
made  by  hand. 

The  reservoir  is  so  pressure  tight,  when  .made  as  described, 


FIG.  101. — Otto  Starting  Gear. 

that  the  author  has  left  one  standing  for  six  weeks  and  started  the 
engine  with  ease  with  what  remained. 

The  starting  is  effected  as  follows  : 

The  engine  is  placed  in  such  position  that  the  motor  crank  is 
on  the  full  in  centre.  The  displacer  is  therefore  half  forward,  the 
reservoir  stop  valve  is  opened,  the  Bunsen  burner  is  lit,  and  the 
gas  cock  of  the  engine  set  at  the  starting  mark.  The  starting 
handle  7  is  then  moved  in,  opening  the  valve  3,  fig.  TOO,  the  gases 

R 


242  The  Gas  Engine 

entering  press  forward  the  displacer  piston  and  fill  the  compres- 
sion space  of  the  engine,  pressing  forward  the  motor  piston  when 
its  crank  comes  off  the  centre.  The  starting  handle  is  then  let 
go,  and  the  motor  piston  runs  over  its  ports  discharging  the  con- 
tents both  of  motor  and  displacer  to  atmosphere.  The  engine  has 
thus  received  a  double  impulse,  one  in  each  cylinder ;  it  is  enough 
to  bring  round  the  piston,  compress  the  mixture  and  get  an  igni- 
tion. One  opening  or  at  most  two  openings  of  the  starting  valve  are 
enough.  The  reservoir  contains  enough  to  give  six  successive  starts. 

After  starting,  the  reservoir  should  be  again  charged  and  closed 
so  that  it  may  be  ready  when  required. 

The  gear  works  very  well  and  is  easily  handled. 

To  those  accustomed  to  see  gas  engines  started  by  hand,  it  is 
somewhat  astonishing  for  the  first  time  to  watch  a  large  machine 
move  away  at  once  by  a  mere  finger  touch  upon  a  valve. 

Starting  Gear — Otto  Engine. — The  starting  gear  used  in  the 
Otto  engine  is  shown  at  fig.  101.  It  consists  of  the  reservoir  i, 
the  charging  and  starting  valve  2  and  a  stop  valve.  The  charging 
valve  is  loaded  so  that  it  does  not  open  with  a  pressure  less  than 
40  Ibs.  per  square  inch,  as  it  communicates  with  the  compres- 
sion space  4.  It  follows  that  the  compression  of  the  charge  in  the 
cylinder  does  not  lift  it,  but  as  soon  as  the  gases  explode,  the 
pressure  lifts  the  valve,  and  the  reservoir  gets  filled  slowly  with 
burned  gases.  If  the  valve  is  left  open  long  enough  the  pressure 
will  rise  to  within  40  Ibs.  of  the  maximum  explosion  pressure,  that 
is,  about  no  Ibs.  per  square  inch  above  atmosphere.  The  stop 
valve  being  screwed  down,  the  gases  are  retained  ready  to  start 
the  engine  when  wanted.  To  start,  the  stop  valve  at  the  reservoir 
is  opened,  and  the  engine  crank  placed  in  such  position  that  it  is 
off  the  centre  and  on  its  impulse  stroke.  The  gases  then  pass 
through  the  valve  2  into  the  cylinder  4,  and  the  valve  2  closes  at 
the  end  of  the  stroke  actuated  by  the  cam  3.  One  impulse  is 
thus  given  and  is  repeated  at  the  proper  time  by  the  action  of  the 
cam  3  upon  2,  through  the  intermediate  lever.  The  pressure  re- 
quired is  high,  because  only  one  forward  movement  of  the  piston 
is  available  for  every  two  revolutions  of  the  engine.  The  twin 
engine  therefore  starts  more  easily  than  the  ordinary  type  of  Otto. 
This  gear  also  works  well ;  it  was  patented  before  the  Clerk  gear, 
but  was  later  in  being  introduced  into  public  use. 


243 


CHAPTER  X, 

THEORIES   OF   THE   ACTION    OF   THE   GASES    IN   THE   MODERN 
GAS    ENGINE. 

THE  general  principles  developed  in  this  work  explaining  the 
causes  of  the  economy  of  the  modern  gas  engine  were  first  enun- 
ciated by  the  author  in  a  paper  read  before  the  Institution  of 
Civil  Engineers  in  April  1882. * 

He  then  classified  gas  engines  in  three  great  groups  : 

Type  i. — Explosion,  acting  on  piston  connected  to  crank.  (No 
compression. ) 

Type  2. — Compression,  with  increase  of  volume  after  ignition, 
but  at  constant  pressure. 

Type  3. — Compression,  with  increase  in  pressure  after  ignition, 
but  at  constant  volume. 

It  was  proved  that  under  comparable  conditions  the  relative 
theoretic  efficiencies  of  the  three  types  were 

Type  i  =  o'2i 
Type  2  =  0-36 
Type  3  =  0-45 

It  was  also  shown  that  in  the  actual  engines  the  real  efficiency 
could  not  be  so  high  as  the  theoretic,  mainly  because  of  the  large 
proportion  of  heat  lost  through  the  sides  of  the  cylinder,  by  the 
exposure  of  the  flame  which  filled  the  cylinder  to  the  comparatively 
cold  enclosing  walls.  A  balance  sheet  was  given  showing  the 
disposal  of  100  heat  units  by  a  compression  engine.  Of  the  TOO 
heat  units,  17 '83  were  converted  into  indicated  work,  29-28  were 

1     The  Theory  of  the  Gas  Engine,'  by  Dugald  Clerk  :  Minutes,  Institute.  Civil 
Engineers,  Lond,  n.     Paper  No.  1855.     April  1882. 

R  2 


244  The  Gas  Engine 

discharged  with  the  exhaust  gases,  and  52-89  units  passed  through 
the  sides  of  the  cylinder  into  the  water  jacket. 

The  economy  of  the  Otto  engine  over  its  predecessors,  the 
Lenoir  and  Hugon  engines,  was  clearly  proved  to  be  due  to  .the 
fact  of  its  using  compression  previous  to  explosion. 

These  conclusions  were  very  generally  accepted  by  scientific 
and  practical  men  who  had  studied  the  subject,  and  in  February 
1884  the  late  Prof.  Fleeming  Jenkin,  then  Professor  of  Engineering 
at  the  University  of  Edinburgh,  delivered  a  lecture  at  the  Institu- 
tion of  Civil  Engineers  in  London,  on  '  Gas  and  Caloric  Engines.' l 
He  had  recalculated  the  efficiencies  due  to  compression,  with  the 
result  of  corroborating  the  present  writer's  conclusions.  He 
states  : 

*  If  I  were  to  compress  gas  to  40  Ibs.,  a  pressure  which  is  used 
not  unfrequently,  the  theoretical  efficiency  would  be  45  per  cent. 
We  actually  get  something  like  24  or  23  per  cent.;  we  know  that 
one-half  of  the  heat  is  taken  away  by  external  cooling.  Thus  we 
find  a  very  close  coincidence  between  the  calculated  efficiency  of 
those  engines  and  that  which  we  actually  obtain,  only  we  throw 
away  about  one-half  of  the  heat  in  keeping  the  cylinder  cool 
enough  to  permit  lubrication.  If  we  compress  to  80  Ibs.  we  have 
a  theoretical  efficiency  of  53  per  cent.  If  we  do  not  compress  at 
all,  as  Mr,  Clerk  has  told  you,  we  have  a  theoretical  efficiency  of 
only  21  per  cent,  so  that  we  have  it  in  our  power  to  increase  the 
theoretical  efficiency  very  greatly  by  increasing  the  pressure  of  the 
gas  and  air  before  ignition.  I  have  no  doubt  that  the  great  gain 
of  efficiency  in  the  Clerk  and  Otto  engines  is  really  due  to  the 
fact  of  the  compression  ;  this  being  done  in  a  workmanlike  way 
and  carried  to  a  very  considerable  point.' 

The  advantages  of  compression  could  not  be  stated  with  more 
clearness  and  truth. 

In  the  same  year  there  was  published  in  Paris  an  able  work 
entitled  '  Etudes  sur  les  Moteurs  a  Gaz  Tonnant,'  by  Professor  Dr. 
Aime  Witz,  of  Lille,  in  which  the  theoretic  efficiencies  of  the  different 
types  of  cycle  are  calculated  for  a  maximum  temperature  of  ex- 
plosion of  1600°  C,  and  temperature  before  explosion  of  15°  C. 

1  '  Heat  in  ts  Mechanical  Applications ':  Institute  Civil  Engineers  Lectures. 
Session  1883-84. 


Theories  of  Action  of  Gases  in  Modern  Gas  Engine    245 

He  adopts  the  same  classification  as  the  present  writer  did  in 
1882,  and  finds  the  efficiencies  : 

Type  i  =  0*28 
Type  2  =  0-38 
Type  3  =  0-44 

which  are  almost  identical  with  the  author's  figures. 

He  also  arrives  at  the  conclusion  that  compression  is  the  great 
source  of  economy  in  the  modern  gas  engine.  At  p.  .53  he  says  : 
'  I  find  myself  again  in  agreement  with  Mr.  Dugald  Clerk  when  he 
affirms  that  the  success  of  Otto  is  due  to  compression  alone,  and 
not  to  the  extreme  dilution  of  the  explosive  mixture  in  the  pro- 
ducts of  the  combustion  of  a  precedent  explosion.' 

He  then  proceeds  to  quote  from  the  present  writer's  paper,  and 
adheres  to  the  statement  that— 

'  Without  compression  previous  to  ignition  an  engine  cannot 
be  produced  giving  power  economically  and  with  small  bulk.' 

Compression  previous  to  ignition  gives  two  great  advantages  : 

(1)  A  thermodynamic   advantage   (improved   theory  of  the 
cycle)  ; 

(2)  Higher  available  pressures  and  smaller  cooling  surfaces 
— the  joint  result  being  an  economy  in  practice  nearly  fourfold 
that  of  the  old  non-compression  engines. 


MR.  OTTO'S  THEORY. 

Previous  to  1882  the  nature  of  the  improvement  obtained  by 
compression  was  imperfectly  understood,  and  this  notwithstanding 
the  very  clear,  though  qualitative,  statements  of  Schmidt,  Million, 
and  Beau  de  Rochas.  An  erroneous  theory  of  the  cause  of  the 
economy  of  the  Otto  engine  was  widely  circulated  and  gained 
considerable  support. 

It  was  enunciated  in  Mr.  Otto  s  specification  of  1876,  No.  2081, 
and  it  was  and  is  still,  so  far  as  the  author  is  aware,  supported  by 
men  so  distinguished  as  Sir  Frederick  Bramwell,  Dr.  Slaby  of 
Berlin,  Prof.  Dewar  of  the  Royal  Institution,  and  Mr.  John 
Imray. 


246  The  Gas  Engine 

According  to  Mr.  Otto,  all  gas  engines,  previous  to  his  patent 
of  1876,  obtained  their  power  from  the  explosion  of  a  homoge- 
neous charge  of  gas  and  air.  By  the  explosion  excessive  heat  was 
evolved,  and  the  pressures  produced  rapidly  fell  away  ;  the  exces- 
sive heat  was  rapidly  absorbed  by  the  enclosing  cold  walls. 

This  caused  great  loss  and  gave  very  wasteful  engines.  Two 
methods  were  open  to  obtain  better  economy  : 

ist,  by  using  a  very  rapid  expansion,  so  that  the  heat  had  but 
little  time  to  be  dissipated  ; 

2nd,  by  using  slow  combustion  ;  that  is,  by  causing  the  in- 
flammable mixture  to  evolve  its  heat  slowly,  so  that  the  production 
of  excessive  temperatures  and  pressures  was  avoided. 

By  the  first  method  all  the  heat  was  supposed  to  be  evolved  at 
once,  and  a  high  temperature  was  produced  :  by  the  second 
method  the  heat  was  evolved  gradually  so  as  to  give  a  low  temper- 
ature and  pressure  which  was  sustained  throughout  the  stroke, 
and  which  was  advantageously  utilised  by  the  piston  while  moving 
at  a  moderate  speed.  Mr.  Otto  states  that  this  gradual  evolution 
of  heat  may  be  produced  by  stratifying  the  charge  of  gas  and  air. 
Instead  of  using  the  homogeneous  charge  of  Lenoir  and  Hugon, 
Mr.  Otto  uses  a  charge  which  he  states  is  not  homogeneous  but 
heterogeneous.  He  affirms  that  his  invention  lies  in  the  method  or 
process  of  forming  this  stratified  charge  in  a  gas-engine  cylinder, 
and  that,  in  addition  to  the  explosive  mixture,  there  must  be  present 
in  the  cylinder  a  mass  of  inert  gas  which  does  not  burn  but  which 
serves  to  absorb  the  heat  of  the  explosion  and  prevent  the  loss 
which  would  otherwise  occur  by  the  cooling  effect  of  the  cylinder 
walls. 

The  *  inert '  gas  may  be  either  air  alone  which  is  capable  of 
supporting  combustion,  or  the  products  of  combustion  which  are 
incapable  of  supporting  combustion,  or  a  mixture  of  both.  It  is 
not  sufficient  that  a  mere  film  of  this  inert  gas  be  present ;  there 
must  be  what  is  termed  a  '  notable '  quantity. 

Mr.  Otto  proposes  to  form  this  heterogeneous  or  stratified 
charge  by  first  drawing  into  the  cylinder  a  charge  of  air  alone ; 
and  second,  a  charge  of  explosive  mixture,  or  by  leaving  in  the 
cylinder  a  sufficient  quantity  of  the  products  of  a  previous  com- 
bustion to  form  a  { notable '  quantity  of  inert  diluent. 


Theories  of  Action  of  Gases  in  Modern  Gas  Engine    247 

The  compression  space  in  the  Otto  engine  is  supposed  to  con- 
tain a  sufficient  volume  of  burned  gases  to  form  the  inert  diluent, 
so  that  the  whole  stroke  of  the  piston  is  available  for  taking  in  the 
explosive  charge. 

Suppose  the  piston  to  begin  its  charging  stroke  :  the  coal-gas 
and  air  mixture  flows  into  the  cylinder  through  the  inlet  port  and 
mixes  to  some  extent  with  the  inert  gas  already  in  the  space  ;  but 
the  mixing  is  incomplete,  and  at  the  piston  itself  the  charge  is 
supposed  to  consist  entirely  of  exhaust  gases.  So  that,  while 
the  charge  at  the  igniting  port  is  readily  explosive,  that  at  the 
piston  is  not  explosive  at  all,  and  between  the  igniting  port  and 
the  piston  the  composition  of  the  charge  varies  from  point  to 
point. 

This  *  arrangement  of  the  gases '  is  supposed  to  be  retained 
during  compression,  and  exist  at  the  moment  of  explosion.  The 
compression  space  contains  a  *  packed  charge,'  which  consists  of 
an  explosive  mixture  at  the  one  end,  and  between  the  explosive 
mixture  and  the  piston  a  cushion  of  inert  fluid,  which  is  uninflam- 
mable and  serves  the  double  purpose  of  relieving  the  piston  from 
the  shock  of  explosion  and  absorbing  heat  which  would  otherwise 
be  lost  by  conduction. 

By  this  device,  heat  is  gradually  evolved.  The  flame  originated 
in  the  port  burns  at  first  with  great  energy  and  spreads  from  one 
combustible  particle  to  another,  more  and  more  slowly  as  it  ap- 
proaches the  piston,  where  the  particles  are  dispersed  more  and 
more  in  the  inert  gas.  The  mixture  is  so  arranged  that  this  burn- 
ing lasts  throughout  the  whole  stroke,  and  is  complete  very  shortly 
before  the  exhaust  valve  opens. 

The  entire  cylinder  is  never  completely  filled  with  flame,  but 
the  charge  at  one  end  has  burned  out  before  the  flame  arrives  at 
the  other  end. 

Dr.  Slaby  comes  forward  in  support  of  this  hypothesis  in  an 
interesting  report  published  as  an  Appendix  to  Prof.  Fleeming 
Jenkins'  lecture  already  referred  to. 

Dr.  Slaby  states  :  '  The  essence  of  Otto's  invention  consists  in 
a  definite  arrangement  of  the  explosive  gaseous  mixture,  in  con- 
junction with  inert  gas,  so  as  to  suppress  explosion  (and  neverthe- 
less insure  ignition). 


248  The  Gas  Engine 

'  At  the  touch  hole,  where  the  igniting  flame  is  applied,  lies  a 
strong  combustible  mixture  which  ignites  with  certainty.  The 
flame  of  this  strong  charge  enters  the  cylinder  like  a  shot,  and 
during  the  advance  of  the  piston  it  effects  the  combustion  of  the 
farther  layers  of  dispersed  gaseous  mixture,  whilst  the  shock  is 
deadened  by  the  cushion  of  inert  gases  interposed  between  the  com- 
bustible charge  and  the  piston. 

'The  complete  action  takes  place  in  a  cycle  of  four  piston 
strokes.  The  first  serves  for  drawing  in  the  gases  in  their  proper 
arrangement  and  mixture ;  the  second  compresses  the  charge  ; 
during  the  third  the  gases  are  ignited  and  expand  ;  and  finally, 
by  the  fourth  the  products  of  combustion  are  expelled.  The 
essential  part  of  the  working  is  performed  by  the  first  of  these 
strokes,  by  which  the  charge  is  drawn  in  and  arranged,  first  air, 
then  dilute  combustible  mixture,  and  finally  strong  combustible 
mixture.  This  arrangement  is  obtained  by  the  working  of  the 
admission  slide.  Moreover,  after  discharge  of  the  products  of 
combustion,  a  portion  remains  in  the  clearance  space  of  the 
cylinder,  and  this  constitutes  the  inert  layer  next  the  piston.  By 
this  peculiar  arrangement  of  the  gases,  the  ignition  and  combus- 
tion above  described  are  rendered  possible,  whilst  the  products  of 
previous  combustion  form  a  cushion,  saving  the  piston  from  the 
shock  of  the  explosion  of  the  strongly  combustible  mixture  at  the 
farther  end  of  the  cylinder.' 

Having  stated  the  essence  of  Otto's  invention,  Dr.  Slaby  pro- 
ceeds to  compare  the  Otto  and  Lenoir  indicator  diagrams,  to  show 
that  the  Otto  diagrams  prove  that  the  above  actions  occur  in  the 
engine.  He  finds  that  the  Otto  expansion  line  is  somewhat  above 
the  adiabatic  line,  and  that  the  Lenoir  expansion  line  'is  below  it. 
That  is,  the  Otto  diagram  gives  evidence  of  heat  being  added  or 
combustion  proceeding  in  the  cylinder  during  the  whole  expansion 
stroke,  and  the  Lenoir  diagram  gives  evidence  of  loss  of  heat,  not 
gain,  during  a  similar  period.  If  a  mass  of  expanding  gas  traces 
on  the  diagram  the  adiabatic  line,  then  it  appears  as  if  no  loss  of 
heat  occurred  ;  but  as  the  temperature  of  the  flame  filling  the 
cylinder  is  known  to  exceed  1200°  C.,  it  must  be  losing  heat  to 
the  water  jacket.  To  make  the  expansion  line  keep  up  to  the 
adiabatic  a  great  flow  of  heat  into  the  gas  must  be  taking  place, 


Theories  of  Action  of  Gases  in  Modern  Gas  Engine    249 

and  as  the  only  source  of  heat  is  combustion,  it  follows  that  the 
gas  is  burning  during  the  expansion  period. 

Dr.  Slaby  calculates  the  proportion  of  heat  evolved  by  the  ex- 
plosion in  the  Otto  engine  as  55  per  cent.,  leaving  45  per  cent,  to 
be  evolved  during  expansion. 

This  he  states  is  due  to  the  portion  of  the  charge  which  con- 
tinues to  burn  after  the  explosion. 

The  curve  differs  from  Lenoir's  in  this,  that  while  in  Lenoir's 
engine  all  the  heat  is  evoked  at  the  moment  of  explosion,  leaving 
none  to  be  evolved  during  expansion,  in  Otto's  only  a  part  is 
evolved  at  first,  and  the  reserved  portion  keeps  up  the  temperature 
during  expansion. 

He  concludes  from  his  experiments  that  the  action  of  the 
Otto  engine  is  truly  as  Mr.  Otto  states  in  his  specification- 
explosion  is  suppressed  and  a  slow  evolution  of  heat  is  obtained, 
and  this  slow  evolution  of  heat  is  the  result  of  the  invention  and 
the  cause  of  the  economy  of  the  engine. 

In  addition  to  this  indirect  proof,  experiments  have  been  made 
at  Deutz  and  elsewhere  to  show  directly  that  stratification  has  a 
real  existence  in  the  Otto  engine. 

An  Otto  engine  was  constructed,  specially  fitted  with  two  igni- 
ting valves  ;  one  valve  was  placed  on  the  side  of  the  cylinder  at 
the  end  of  the  explosion  space  next  the  piston,  so  that  it  could 
ignite  the  gases  at  the  piston  ;  the  other  valve  was  the  usual  one 
at  the  end  of  the  cylinder,  igniting  the  gases  in  the  admission 
port. 

Experiments  were  made  to  discover  if  the  side  valve  would 
fire  the  mixture  at  the  piston  ;  it  was  found  that  it  did  so.  Con- 
secutive ignitions  were  obtained  there. 

Diagrams  were  taken  for  comparison,  with  the  end  and  the 
side  valves  in  alternate  action,  care  being  taken  to  keep  the  charge 
in  the  same  proportions  during  the  trials.  It  was  found  that 
although  the  side  valve  ignited  as  regularly  as  the  end  valve,  yet 
the  diagrams  were  different.  Instead  of  the  usual  rapid  ascending 
explosion  line,  the  explosion  took  place  more  slowly,  and  the 
maximum  pressure  was  not  attained  till  late  in  the  stroke. 

The  ignitions  were  slower  from  the  side  valve  than  from  the 
end  valve.  If  an  uninflammable  cushion,  such  as  Dr.  Slaby  so 


250  The  Gas  Engine 

clearly  describes,  existed  at  the  piston,  one  would  expect  that  the 
side  valve  would  fail  entirely,  but  it  ignited  quite  regularly  although 
more  slowly  than  the  end  valve. 

This  experiment  is  considered  to  prove  stratification. 

To  make  stratification  visible  to  the  eye,  a  small  glass  mode 
was  constructed.  It  consisted  of  a  glass  cylinder  of  about  \\  ins. 
internal  diameter,  containing  a  tightly  packed  piston  connected  to 
a  crank  ;  the  stroke  was  about  6  ins.  ;  when  full  back,  the  piston 
left  a  considerable  space  to  repiesent  the  explosion  space.  A 
brass  cover  was  fitted  to  the  end  of  the  tube,  and  in  it  was  bored 
a  hole  of  about  f  in.  diameter,  representing  the  admission  port ; 
in  this  hole  was  screwed  a  pet  cock  to  which  a  cigarette  was 
affixed. 

On  lighting  the  cigarette  and  then  moving  the  piston  forward 
by  the  crank,  it  was  seen  that  the  smoke  of  the  cigarette  which 
passed  in  did  not  completely  fill  the  cylinder ;  the  smoke  slowly 
oozed  in  and  left  a  large  clear  space  between  it  and  the  piston. 
The  smoke  was  supposed  to  represent  the  charge  of  gas  and  air 
rushing  in,  and  the  clear  air  behind  the  piston  the  cushion  which 
was  said  to  exist  in  the  Otto  engine.  It  was  supposed  that  in  the 
glass  cylinder  was  repeated  on  a  small  scale  the  action  of  the  gases 
occurring  on  a  larger  scale  in  the  Otto  engine.  In  a  recent  paper 
in  a  German  engineering  journal,  Dr.  Slaby  recounts  this  experi- 
ment, and  lays  great  weight  upon  it.  He  considers  that  it  un- 
doubtedly proves  the  truth  of  the  Otto  theory. 

In  discussion  Mr.  John  Imray  concisely  states  the  Otto 
position  as  follows  : 

'The  change  which  Mr.  Otto  had  introduced,  and  which 
rendered  the  engine  a  success  was  this  :  that  instead  of  burning 
in  the  cylinder  an  explosive  mixture  of  gas  and  air,  he  burned  it 
in  company  with,  and  arranged  in  a  certain  way  in  respect  of,  a 
large  volume  of  incombustible  gas  which  was  heated  by  it,  and 
which  diminished  the  speed  of  combustion.' 

And  Mr.  Bousfield  states  it  in  similar  terms  : 

'  In  the  Otto  gas  engine  the  charge,  varied  from  a  charge 
which  was  an  explosive  mixture  at  the  point  of  ignition  to  a  charge 
which  was  merely  an  inert  fluid  near  the  piston.  When  ignition 
took  place,  there  was  an  explosion  close  to  the  point  of  ignition 


Theories  of  Action  of  Gases  in  Modern  Gas  Engine    251 

that  was  gradually  communicated  throughout  the  mass  of  the 
cylinder.  As  the  ignition  got  further  away  from  the  primary  point 
of  ignition,  the  rate  of  transmission  became  slower,  and  if  the 
engine  were  not  worked  too  fast  the  ignition  should  gradually 
catch  up  the  piston  during  its  travel,  all  the  combustible  gas  being 
thus  consumed.  When  the  engine  was  worked  properly  the  rate 
of  ignition  and  the  speed  of  the  engine  ought  to  be  so  timed  that 
the  whole  of  the  gaseous  contents  of  the  cylinder  should  have 
been  burned  out  and  have  done  their  work  some  little  time  before 
the  exhaust  took  place,  so  that  their  full  effect  could  be  seen  in 
the  working  of  the  engine.  This  was  the  theory  of  the  Otto  engine.' 
From  these  quotations  it  will  be  seen  that  Mr.  Otto's  supporters 
agree  that  Mr.  Otto  has  invented  a  means  of  suppressing  explosion, 
and  substituting  for  explosion  a  regulated  combustion,  and  that 
this  process  is  the  cause  of  the  economy  of  the  engine.  They 
are  agreed  that  he  has  succeeded  in  preventing  explosion,  and 
that  he  does  this  by  arranging  or  stratifying  the  charge  which  is 
to  be  used.  They  consider  that  engines  previous  to  Mr.  Otto's 
were  wasteful  because  they  used  a  homogeneous  and  therefore 
explosive  charge,  and  that  Mr.  Otto's  engine  is  economical  be- 
cause it  uses  a  heterogeneous  or  stratified  charge,  which  is  con- 
sequently non-explosive. 

Discussion  of  Mr.  Otto's  Theory. 

The  primary  fallacy  of  Mr.  Otto's  theory  lies  in  the  assumption 
that  previous  engines  were  more  explosive  than  his,  and  that  in 
previous  engines  all  the  heat  was  evolved  at  once  :  as  a  plain 
matter  of  fact  this  is  incorrect.  In  the  Lenoir  and  Hugon  engines, 
as  in  all  explosive  engines,  little  more  than  one-half  of  the  total 
heat  is  evolved  by  the  explosion,  and  the  portion  reserved  is  evolved 
during  the  stroke  of  the  engine. 

The  following  test  of  a  Lenoir  engine,  made  by  the  author  in 
London,  very  clearly  shows  the  suppression  of  heat  at  first : 

Lenoir  engine  rated  at  one  horse  power. 
Cylinder  7^  inches  diameter  ;  stroke  nf  inches. 
Average  revolutions  during  test,  85  per  minute. 
Gas  consumed  in  one  hour,  86  cubic  feet. 


252  The  Gas  Engine 

With  full  load,  indicated  horse  power,   1-17    (average   of  9 

diagrams). 
Gas  consumed  per  indicated  horse  power  per  hour,  73-5  cubic 

feet. 

Maximum  temperatures  of  explosion,  1100°  to  1200°  C. 
Mixture  in  engine  i  vol.  coal  gas,  12-5  vols.  of  air  and  other 

gases. 
Heat  evolved  by  explosion,  60  per  cent,  of  total  heat. 

The  proportion  of  the  mixture  was  calculated  from  the  points  of 
cut-off  on  the  diagram,  and  after  making  allowance  for  the  volume 
of  burned  gases  in  the  clearances  of  the  engine.  It  will  be 
observed  that  only  60  per  cent,  of  the  gas  is  burned  at  first,  leaving 
40  per  cent,  to  be  burned  during  the  stroke,  and  also  that  the 
temperature  of  the  explosion  never  exceeds  1200°  C.  Now  in  the 
Otto  engine,  according  to  Thurston,  60  per  cent,  of  the  heat  is 
evolved  at  explosion,  and  40  afterwards,  and  the  usual  maximum 
temperature  is  about  1600°  C.  So  that,  so  far  as  the  slowness  of 
the  explosion  is  concerned,  there  is  no  difference,  and  in  the  in- 
tensity of  the  temperature  produced,  the  Otto  exceeds  the  Lenoir. 

It  is  difficult  to  understand  how  Dr.  Slaby  could  fall  into  so 
obvious  an  error  as  he  did,  and  suppose  that  more  heat  was  kept 
back  in  the  case  of  the  Otto  explosion.  At  the  time  he  wrote  his 
report,  accounts  of  Hirn's,  Bunsen's,  and  Mallard's  experiments 
on  explosion  were  in  existence,  all  of  them  agreeing  on  the  fact 
of  a  large  suppression  of  heat  at  the  maximum  temperature  of  the 
explosion,  although  differing  in  the  explanation  of  the  fact. 

Hirn  even  stated  that  in  the  Lenoir  engine  the  pressures  fell 
far  short  of  what  should  be,  if  all  the  heat  were  evolved  at  once. 
Yet  Dr.  Slaby,  in  the  presence  of  all  this  definite  and  carefully 
ascertained  knowledge,  is  astonished  when  he  finds  only  55  per 
cent,  of  the  total  heat  evolved  by  the  explosion  in  the  Otto  engine, 
and  the  only  explanation  which  occurs  to  him  is  that  of  stratifica- 
tion. 

If  stratification  exists  at  all  in  the  engine,  then  it  produces  no 
measurable  change  in  the  explosion  ;  it  neither  retards  the  evolu- 
tion of  heat,  nor  does  it  moderate  the  temperature. 

The  explosion  and  expansion  curves  are  precisely  what  they 
would  have  been  with  a  homogeneous  charge. 


Theories  of  Action -of  Gases  in  Modern  Gas  Engine    253 

•  The  mere  fact  that  heat  is  suppressed  in  the  Otto  explosion 
proves  nothing,  because  a  precisely  equivalent  amount  of  heat  is 
suppressed  in  all  gaseous  explosions,  and  Dr.  Slaby's  contention, 
based  upon  the  supposed  peculiarity  of  the  Otto,  falls  to  the 
ground. 

Dr.  Slaby  has  been  led  into  error  by  the  fact  that  the  expansion 
line  of  the  Lenoir  diagram  falls  below  the  adiabatic,  while  the 
expansion  line  of  the  Otto  diagram  remains  slightly  above  it  or 
upon  it.  He  assumes  that  in  the  Lenoir  no  heat  is  being  added 
during  expansion,  whereas  just  as  much  heat  is  being  added,  or 
just  as  much  combustion  i(j  proceeding  during  the  Lenoir  stroke, 
only  the  cooling  of  the  cylinder  walls  is-  greater,  and  the  heat  is 
abstracted  so  rapidly  that  the  line  falls  below  the  adiabatic.  This 
is  due  to  two  causes,  (i)  the  greater  proportional  cooling  surface 
exposed  by  the  Lenoir  engine,  and  (2)  a  longer  time  of  exposure. 
The  absence  of  compression  and  the  slow  piston  speed  makes  the 
loss  greater. 

Although  quite  as  much  heat  is  evolved  during  the  stroke,  it 
is  overpowered  by  the  greater  cooling,  and  the  line  falls  under  the 
adiabatic.  This  fall  is  evidence  of  greater  cooling,  not  of  less 
evolution  of  heat. 

In  a  recent  paper,1  'Die  Verbrennung  in  der  Gasmaschine, 
Professor  Schottler  makes  this  explanation  of  the  difference  be- 
tween the  lines,  and  states  that  *  Whether  stratification  exists  or 
does  not  exist  in  the  Otto  engine  it  is  unnecessary,  and  is  not  the 
cause  of  the  slow  falling  of  the  expansion  line.'  In  all  crucial 
points  the  Otto  theory  breaks  down,  as  proved  by  diagrams  taken 
from  his  engine. 

The  explosion  is  not  suppressed  ;  the  maximum  temperatures 
produced  are  not  lower  than  those  previously  used  ;  the  mixture 
used  is  not  more  diluted  than  in  the  previous  engines,  and  the  in- 
tensity of  the  pressures,  as  well  as  the  rate  of  their  application,  is 
greater. 

The  mixture  in  the  engine  from  Slaby's  figures  is  i  vol.  coal 
gas  to  10-5  vols.  of  other  gases,  and  from  Thurston's  figures  i 
vol.  coal  gas  to  9-1  vols.  of  other  gases,  while  Lenoir  often  used 
i  vol.  gas  to  12  of  air. 

1  Zeitschrift  des  Vereines  deutscher  Ingenieure.     Band  xxx.,  Seite  209.   - 


254  The  Gas  Engine 

The  engine  instead  of  using  a  less  explosive  power  than  the 
Lenoir  engine  uses  one  more  intensely  explosive. 

The  effect  of  the  reduction  of  cooling  surface  and  increase  of 
piston  velocity  is  to  diminish  the  loss  of  heat  to  the  cylinder  walls, 
and  the  slowly  descending  line  is  not  the  cause  of  the  economy, 
but  is  the  effect  and  evidence  of  it. 

Stratification. — The  inquiry  into  the  existence  or  non-existence 
of  stratification  in  the  cylinder  has  no  practical  bearing  on  the 
question  of  economy,  as  the  explosion  curves  act  precisely  as  they 
would  with  homogeneous  mixtures.  Scientifically,  however,  the 
question  is  interesting  and  will  be  shortly  considered. 

The  evidence  which  it  is  considered  proves  its  existence  in  the 
Otto  engine  is  in  the  author's  opinion  most  unsatisfactory.  Dr. 
Slaby  distinctly  asserts  the  existence  of  an  inert  stratum  next  the 
piston,  'interposed  between  the  combustible  charge  and  the  piston,' 
and  Mr.  Imray  speaks  of  the  'arrangement  of  the  charge  in  respect 
of  a  large  volume  of  incombustible  gases/  and  Mr.  Bous field  of 
'a  charge  which  was  merely  an  inert  fluid  next  the  piston.'  Yet 
all  the  evidence  in  support  of  these  positive  assertions  is  given  by 
one  experiment  made  with  an  Otto  engine,  and  one  with  a  small 
glass  model.  The  evidence  given  by  the  experiment  on  the  engine 
itself,  in  the  author's  opinion,  disproves  stratification  in  the  Otto 
sense  altogether.  If  the  inert  stratum  next  to  the  piston  had  any 
real  existence,  then  the  side  igniting  valve  in  the  experiment  made 
by  Mr.  Otto,  should  not  have  ignited  the  mixture  at  all.  The  fact 
that  it  did  ignite  regularly  and  consecutively,  proved  most  dis- 
tinctly that  the  gas  next  the  piston  was  not  inert  but  was  explosive, 
and  being  explosive  in  itself  it  could  not  act  as  a  cushion  to 
absorb  heat  or  shock.  That  experiment  alone  settles  the  ques- 
tion, and  proves  at  once  the  visionary  nature  of  the  cushion  of 
inert  gas  next  the  piston. 

The  fact  that  the  ignitions  were  slower  than  those  from  the  end 
slide  does  not  get  rid  of  the  fact  that  ignition  did  take  place,  and 
to  those  who  understand  the  sensitive  nature  of  any  igniting  valve, 
it  will  not  be  difficult  to  comprehend  how  small  a  difference  in 
adjustment  will  cause  late  and  slow  ignitions.  At  the  very  utmost 
the  experiment  points  to  a  small  difference  in  the  dilution  of  the 
explosive  mixture  at  the  piston  and  that  at  the  end  port. 


Theories  of  Action  of  Gases  in  Modern  Gas  Engine    255 

Experiments  made  by  the  author  also  prove  that  the  mixture 
in  the  Otto  cylinder  is  present  in  explosive  proportions  close  up  to 
the  piston.  The  piston  of  a  3^  HP  Otto  engine  was  bored  and 
fitted  with  a  screw  plug,  which  carried  a  small  spiral  of  platinum 
wire  in  electrical  connection  with  a  battery ;  the  platinum  spiral 
projected  from  the  inner  surface  of  the  piston  by  a  quarter 
of  an  inch.  When  the  engine  was  running  in  the  usual  way,  the 
wire  was  made  incandescent  by  the  battery  and  the  external  light 
was  put  out.  It  was  proved  that  by  a  little  care  in  getting  the 
platinum  to  a  certain  temperature,  the  engine  worked  as  usual, 
igniting  regularly  and  consecutively.  The  spiral  was  made  just 
hot  enough  to  ignite  when  compression  was  complete,  but  not  hot 
enough  to  ignite  before  compressing.  If  an  incombustible  stratum 
had  existed  even  so  close  to  the  piston  as  £  in.  then  the  wire 
should  never  have  been  able  to  ignite  the  charge  at  all.  If  the 
wire  was  made  too  hot,  then  ignition  often  took  place  while  the 
charge  was  still  entering,  proving  that  no  stratification  existed  even 
while  the  charge  was  incomplete.  A  little  consideration  of  the 
arrangement  of  the  Otto  engine  will  show  that  stratification  can- 
not have  any  existence  in  it.  The  end  of  the  combustion  space  is 
usually  flat,  and  sometimes  the  admission  port  projects  slightly 
into  it ;  the  area  of  the  admission  port  is  about  ^  of  the  piston 
area  ;  accordingly  the  entering  gases  flow  into  the  cylinder  at  a 
velocity  thirty  times  the  piston  velocity,  or  at  the  Otto  piston 
speed,  about  120  miles  an  hour. 

Great  commotion  inevitably  occurs  ;  the  entering  jet  projects 
itself  through  the  gases  right  up  against  the  piston,  and  then  re- 
turns eddying  and  whirling  till  it  mixes  thoroughly  with  whatever 
may  be  in  the  cylinder.  The  mixture  becomes  practically  homo- 
geneous even  before  compression  commences. 

Experiments  made  by  Dr.  John  Hopkinson  and  the  author  on 
full  size  glass  models  of  the  Otto  cylinder  show  this  mixing  action 
very  beautifully.  A  3^  HP  Otto  cylinder  was  copied  in  every 
proportion  in  glass,  and  the  valve  was  so  arranged  that  it  passed  a 
charge  of  smoke  at  the  proper  time.  The  pistcn  was  placed  at 
the  end  of  its  stroke,  leaving  the  compression  space  filled  with  air. 
When  pulled  forward  the  valve  opened  to  a  chamber  filled  with 
smoke,  and  the  smoke  rushed  through  the  port,  projected  right 


256  '  The  Gas  Engine 

through  the  air  in  the  space,  struck  the  piston,  and  filled  the 
cylinder  uniformly,  much  faster  than  the  eye  could  follow  it.  it 
mixed  instantaneously  with  the  air  in  the  cylinder  without  evincing 
the  slightest  tendency  to  arrange  itself  in  the  manner  imagined 
by  Mr.  Otto.  Mr.  Otto's  experiment  with  a  cigarette  and  glass 
cylinder  does  not,  in  the  most  remote  degree,  imitate  the  condi- 
tions occurring  in  his  engine;  the  proportions  are  quite  wrong. 
The  model  is  much  too  small,  and  the  glass  cylinder  is  too  long 
in  proportion  to  its  diameter ;  then  the  gases  are  so  badly  throttled 
by  passing  through  the  cigarette,  that  when  the  piston  is  moved 
forward  it  leaves  a  partial  vacuum  behind  it,  and  only  a  little 
smoke  enters,  not  nearly  enough  to  follow  up  the  piston,  but 
only  sufficient  to  ooze  into  the  back  of  the  cylinder  while  the 
piston  moves  forward  and  expands  the  air  which  is  already  in  the 
cylinder.  It  was  easy  for  Mr.  Otto  to  have  copied  his  cylinder 
and  valve  full  size  and  imitated  precisely  the  conditions  existing  in 
his  engines. 

Had  he  done  this  he  would  have  proved  complete  mixing  in- 
stead of  stratification.  Why  did  he  refrain  from  doing  this  ?  The 
question  at  issue  is  not,  Can  stratification  be  obtained  by  a  speci 
ally  devised  form  of  apparatus — no  one  doubts  that  it  can — but, 
Does  stratification  exist  in  the  Otto  engine  ?  If  it  does  not 
exist  in  the  Otto  engine  then  it  is  perfectly  plain  that  it  cannot  be 
the  cause  of  the  economy  of  the  motor,  and  it  is  quite  certain  that 
it  cannot  exist  in  the  Otto  engine.  Prof.  Schottler,  in  the  paper 
already  referred  to,  also  arrives  at  the  conclusion  that  stratification 
has  no  existence  in  the  Otto  engine,  and  that  Mr.  Otto's  small 
glass  model  does  not  truly  represent  the  actions  occurring  in  the 
engine. 

In  all  gas  engines,  when  the  charge  enters  the  cylinder  through 
a  port  the  residual  gases  in  the  port  are  swept  into  the  cylinder, 
and  while  the  port  itself  is  filled  with  gas  and  air  mixture,  free 
from  admixture  with  residual  gases,  the  cylinder  contains  the  gas 
and  air  mixture  diluted  with  whatever  residual  gases  exist  in 
the  engine  which  have  not  been  expelled  by  the  piston.  The 
mixture  in  the  port  is  accordingly  stronger  and  more  inflammable 
than  the  mixture  in  the  cylinder. 

In  the  Lenoir  and  Hugon  engines  this  occurred  to  a  marked 


Theories  of  Action  of  Gases  in  Modern  Gas  Engine    257 

extent ;  m  the  Hugon  engine  as  much  as  30  per  cent,  of  the  whole 
charge  consisted  of  residual  gases,  and  the  charge  in  the  cylinder 
was  considerably  more  dilute  than  that  in  the  admission  port.  In 
the  Otto  engine  this  also  occurs,  but  it  is  not  stratification,  and  it 
is  not  a  new  invention  ;  the  cylinder  is  filled  with  explosive  mix- 
ture more  dilute  than  that  in  the  ignition  port,  but  still  explosive 
throughout. 


CAUSES  OF  THE  SUPPRESSION  OF  HEAT  AT  MAXIMUM 
TEMPERATURE  IN  GASEOUS  EXPLOSIONS. 

Although  experimenters  are  unanimously  agreed  upon  the  fact  of 
the  suppression  of  heat  at  the  maximum  temperatures  produced  by 
gaseous  explosions,  they  differ  widely  in  their  explanation  of  the 
causes  producing  this  suppression. 

Three  principal  theories  have  been  proposed —     * 

1.  Theory  of  Limit  by  Cooling. — This  is  Hirn's  theory,  and  it 
assumes  that  when  explosion  occurs,  a  point  is  reached  when  the 
cooling  effect  of  the    enclosing  walls    is    so  great  that  heat  is 
abstracted  more  rapidly  than  it  is  evolved  by  the  explosion,  and 
accordingly  the  temperature  ceases  to  increase  and  begins  to  fall. 

The  maximum  temperature  falls  short  of  what  it  would  do  if 
no  heat  were  lost  during  the  progress  of  the  explosion  to  the  walls. 
If  it  be  true  that  the  cold  surface  of  the  vessel  is  the  limiting 
cause,  then  the  maximum  pressure  produced  in  exploding  the 
same  gaseous  mixture,  in  vessels  of  different  capacity,  will  greatly 
vary.  When  the  vessel  is  small  and  the  surface  therefore  re- 
latively large,  more  heat  should  be  abstracted  and  lower  pressure 
should  be  produced.  This  is  not  the  case.  The  maximum  tem- 
perature produced  by  an  explosion  is  almost  independent  of  the 
capacity  of  the  vessel.  Surface  does  not  control  maximum  tem- 
perature, although  increased  surface  increases  the  rapidity  of  the 
fall  of  temperature  after  the  point  of  maximum  temperature. 

2.  Theory  of  Limit  by  Dissociation. — This  is  Bunsen's  theory, 
and  it  is  undoubtedly  largely  true.     The  fact  that  no  unlimited 
temperature  can  be  attained  by  combustion,  even  when  the  use  of 
non-conducting  materials  prevents  cooling  almost  completely,  is 
so  conclusively  established  by  science  and  practice  that  gradual 

a 


2  58  The  Gas  Engine 

combustion  due  to  dissociation  may  be  safely  taken  as  occurring 
to  a  considerable  extent  at  the  higher  temperatures  used  in  gas 
engines.     But  there  is  a  difficulty  in  its  application  to  all  cases. 
In  experiments    made  with    explosions   in   a   closed  vessel   the 
suppression  of  heat  is  almost  the  same  at  low  temperatures  as  at 
high  temperatures ;  thus  with  hydrogen  mixtures- 
Max,  temp,  of  explosion    900°  C.  ;  apparent  evolution  of  heat  55  per  cent. 
1700°  C.  „  „  ,,      54 

If  dissociation  were  the  sole  cause,  then  as  water  must  dissociate 
more  at  the  higher  temperature  than  at  the  lower,  the  apparent 
evolution  of  heat  should  be  less  at  1 700°  C.  than  at  900°  C.  It 
is  not  so.  Some  other  cause  than  dissociation  must  therefore  be 
acting  to  check  the  increase  of  temperature  so  powerfully  at 
900°  C. 

3.  Theory  of  Limit  by  the  Increasing  Specific  Heat  of  the  Heated 
Gases. — Messrs.  Mallard  and  Le  Chatelier  have  advanced  the  theory 
that  up  to  temperatures  of  about  1800°  C.  dissociation  does  not 
act  at  all  or  only  to  a  trifling  extent.  They  consider  that  the 
gases  are  completely  combined  or  burned  at  the  maximum 
temperature  of  the  explosion.  But  the  specific  heat  of  nitrogen, 
oxygen,  and  the  products  of  combustion  increases  with  increasing 
temperature,  becoming  nearly  doubled  when  approaching  2000°  C. 
The  apparent  limit  is  due,  not  to  the  suppression  of  combustion 
as  required  by  the  dissociation  theory,  nor  to  the  loss  of  heat 
by  the  theory  of  cooling,  but  to  the  absorption  of  the  heat  which 
is  completely  evolved  by  the  increasing  capacity  for  heat  of  the 
ignited  gases.  The  same  objection  applies  to  this  as  to  the 
dissociation  theory.  If  it  were  entirely  true  that  specific  heat 
increased  with  increasing  temperature,  a  greater  proportion  of 
heat  would  apparently  be  evolved  at  the  lower  temperatures,  which 
is  not  always  the  case. 

It  is  impossible  to  discriminate  between  the  effect  produced 
by  increased  specific  heat  and  the  effect  produced  by  dissociation 
on  the  explosion  curves. 

Those  are  the  three  principal  theories  which  have  been  pro- 
posed, and  in  the  author's  opinion  none  of  them  completely  explains 
the  facts.  The  phenomena  of  explosion  are  very  complex,  and 


Theories  of  Action  of  Gases  in  Modern  Gas  Engine    259 

no  single  cause  explains  the  limit  and  other  phenomena  of 
gaseous  explosion.  These  phenomena  are  more  complex  than 
have  generally  been  supposed.  In  many  chemical  combina- 
tions it  has  been  proved  by  Messrs.  Vernon-Harcourt  and 
Esson,  and  Dr.  E.  J.  Mills  and  Dr.  Gladstone,  that  the  rate  at 
which  the  reaction  proceeds  depends  upon  the  proportions  ex- 
isting between  the  masses  of  the  acting  substances  present,  and 
those  neutral  to  the  reaction,  and  that  combination  proceeds 
more  slowly  as  dilution  increases.  From  this  it  follows,  that  in  a 
combination  where  no  diluent  is  present,  the  fiist  part  of  the 
action  is  more  rapid  than  the  last ;  at  first  all  the  molecules  in 
contact  are  active,  but  after  some  combination  has  occurred  the 
product  acts  as  a  diluent.  The  last  portion  of  the  reaction, 
having  to  proceed  in  the  presence  of  the  greatest  dilution,  is 
comparatively  slow.  Such  an  action  the  author  considers  occurs 
in  all  gaseous  explosions,  and  is  one  of  the  causes  preventing 
the  complete  evolution  of  all  the  heat  present  at  the  moment  of 
the  explosion. 

The  subject  is  a  difficult  one,  and  more  experiment  is  required 
for  its  complete  settlement. 


s  2 


26o  The  Gas  Engine 


CHAPTER  XL 

THE  FUTURE  OF  THE  GAS  ENGINE. 

SINCE  1860,  when  by  the  genius  and  perseverance  of  M.  Lenoir 
the  gas  engine  first  emerged  from  the  purely  experimental  stage, 
it  has  steadily  and  continually  increased  in  public  favour  and  use- 
fulness. At  first  more  wasteful  of  heat  than  the  steam  engine,  it 
is  now  more  economical  ;  at  first  delicate  and  troublesome  in  the 
extreme,  it  is  now  firmly  established  as  a  convenient,  safe  and 
reliable  motor  ;  at  first  only  available  for  small  and  trifling  powers, 
now  really  large  and  powerful  motors  are  used  in  thousands. 
Many  inventors  have  contributed  to  its  progress,  but  its  present 
position  is  in  the  main  due  to  the  patie-nce,  energy  and  command- 
ing ability  of  one  man — Mr.  Otto. 

In  1860,  the  efficiency  of  the  gas  engine  was  only  4  per  cent.;  in 
1886,  the  efficiency  of  the  best  compression  engines  is  18  percent. 

That  is,  at  first  a  gas  engine  could  only  convert  4  out  of  every 
100  heat  units  given  to  it  into  mechanical  work,  as  developed  in 
the  motor  cylinder  ;  now  it  can  give  18  out  of  every  100  units  as 
indicated  work. 

Having  advanced  in  economy  more  than  fourfold  in  the  past 
twenty-five  years,  what  limits  exist  to  check  its  progress  in  the 
future  ? 

Apart  from  the  greater  perfection  of  the  mechanical  arrange- 
ments of  the  gas  engines  of  to-day,  the  great  cause  of  improve- 
ment since  1860  is  the  successful  introduction  of  the  compression 
principle. 

Can  this  principle  be  much  further  extended  in  its  application? 
In  the  author's  opinion,  No. 

By  undue  increase  of  compression  the  negative  work  of  the 
engine  would  be  much  increased,  and  the  strains  would  become 


The  Future  of  the  Gas  Engine  261 

so  great  that  heavier  and  more  bulky  engines  would  be  required 
for  any  given  power.  Friction,  due  to  this,  increases  more  rapidly 
than  efficiency  ;  consequently  the  gain  in  indicated  efficiency 
would  be  more  than  compensated  by  loss  of  effective  power.  Im- 
provement must  be  sought  elsewhere. 

The  most  obviously  weak  point  of  the  present  engine  is  insuffi- 
cient expansion.  In  the  Otto  engine  the  exhaust  valve  opens 
while  the  gases  in  the  cylinder  are  still  at  a  pressure  of  30  pounds 
per  square  inch  above  atmosphere  ;  in  the  Clerk  engine  the 
pressure  is  sometimes  as  high  as  35  pounds  per  square  inch  above 
atmosphere  at  the  moment  of  exhaust. 

The  gas  engines  discharge  pressures,  without  utilising  them, 
with  which  many  steam  engines  commence. 

There  is  evident  waste  here,  which  can  be  remedied  by  using 
further  expansion.  In  continuing  expansion  the  loss  of  heat  to 
the  cylinder  would  not  be  so  great  as  in  the  earlier  part  of  the 
diagram,  because  the  temperature  is  greatly  reduced ;  it  may 
therefore  be  supposed,  without  appreciable  error,  that  the  added 
portion  of  the  diagram  would  give  at  least  as  good  a  result  when 
compared  with  its  theoretical  efficiency  as  the  earlier  part.  If  the 
expansion  be  carried  so  far  that  the  pressure  falls  to  atmosphere, 
then  the  theoretical  efficiency  of  an  Otto  engine  would  be  0-5  ; 
theoretically  its  cycle  would  then  be  able  to  convert  50  per  cent, 
of  the  heat  given  to  it  into  indicated  work  ;  practically  the  com- 
pression gas  engine  at  present  converts  one-half  of  what  theory 
allows  ;  therefore  with  the  greater  expansion  it  may  be  expected 
to  give  one-half  of  50  per  cent. — that  is,  expansion  only  will  raise 
the  practical  efficiency  from  18  per  cent,  to  25  per  cent. 

By  complete  expansion  to  atmosphere,  the  gas  consumption 
of  an  Otto  or  Clerk  engine  could  be  reduced  from  20  cubic  feet 
per  IHP  hour,  to  14-5  cubic  feet  per  IHP  hour.  There  are, 
of  course,  practical  difficulties  in  the  way  of  expanding,  but  they 
will  be  overcome  in  time.  Mr.  Otto  has  attempted  greater  ex- 
pansion in  various  ways,  and  so  has  the  author,  but  as  yet  neither 
has  succeeded  in  carrying  it  beyond  the  experimental  stage. 

It  must  not  be  supposed,  as  it  too  often  is,  that  a  high 
exhaust  pressure  means  an  uneconomical  engine,  or  that  compari- 
sons of  pressure  of  exhaust  give  the  smallest  clues  to  the  relative 


262  The  Gas  Engine 

economy  of  engines.  It  is  a  very  common,  but  a  very  erroneous, 
belief  that  if  the  pressure  in  the  cylinder  of  a  gas  engine  is  very 
near  atmospheric  pressure  when  the  exhaust  valves  open,  that 
fact  is  a  proof  that  the  engine  is  economical. 

This  is  not  so — indeed,  it  may  be  the  very  reverse. 

In  engines  of  type  3,  for  example,  in  which,  as  in  the  Otto  and 
Clerk  engines,  the  expansion  after  explosion  is  carried  to  the 
initial  volume  existing  before  explosion  and  no  further,  it  has 
already  been  shown  that  the  actual  indicated  efficiency  is  quite 
independent  of  the  increase  of  temperature  above  the  temperature 
of  compression.  That  is,  the  temperature  of  the  explosion  may 
be  anything  whatever  above  the  temperature  of  compression  with- 
out either  increasing  or  diminishing  the  indicated  economy. 

Suppose  an  Otto  diagram  with  three  expansion  lines,  (i)  max. 
temp.  600°  C,  (2)  max.  temp.  1000°  C.,  and  (3)  max.  temp. 
1600°  C,  the  maximum  temperatures  in  the  three  cases  being 
attained  at  the  beginning  of  the  stroke,  the  efficiency  of  these  three 
lines  is  identical.  Of  course  the  total  indicated  power  increases 
with  increase  of  temperature,  and  diminishes  with  diminution  of 
temperature,  but  the  proportions  of  the  heat  given  by  the  engine 
as  work  in  the  three  cases  remain  constant. 

The  same  thing  applies  to  any  number  of  intermediate  tern- 
peratures. 

It  might  be  supposed  that  the  line  i  by  expanding  more  nearly 
to  atmosphere  would  be  the  more  economical,  and  that  the  line  3, 
because  of  the  high  pressure  of  exhaust,  was  the  more  wasteful. 

It  is  a  peculiarity  of  this  cycle,  with  the  expansion  stated, 
that  the  efficiency  is  absolutely  dependent  upon  compression 
alone — that  is,  the  ratio  of  volume  before  and  after  expansion — and 
is  quite  independent  of  the  maximum  temperature. 

The  case  at  once  alters  if  expansion  be  carried  to  atmosphere. 
Here  the  line  3  would  give  far  greater  economy  than  the  others, 
and  efficiency  would  increase  with  increase  of  explosion  tempera- 
ture. 

Suppose  complete  expansion  successfully  applied  to  the  gas 
engine,  and  an  actual  indicated  efficiency  of  25  per  cent,  attained, 
can  any  further  improvement  be  hoped  for  ? 

What  causes  the  difference  still  existing  between  theory,  which 


The  Future  of  the  Gas  Engine  263 

shows  a  possible  50  per  cent.,  and  practice,  which  may  now  realise 
25  per  cent.  ? 

The  great  loss  is  heat  flowing  from  the  exploded  gases  through 
the  cylinder  walls.  Dr.  Slaby's  balance-sheet  of  the  Otto  engine 
shows — 

Per  cent. 

Work  indicated  in  cylinder .         .        .         .        .     i6x> 
Heat  lost  to  cylinder  walls   .         .         .         .  51  x> 

Heat  carried  away  by  exhaust      .         .         .         .31*0 
Heat  lost  by  radiation,  etc.  .        .        .  2-o 

100 

By  expanding  as  described  it  would  be  altered  as  follows  : 

Per  cent. 

Work  indicated  in  cylinder 25-0 

Heat  lost  to  cylinder  walb 51-0 

Heat  carried  away  by  exhaust      .         .         .         .22-0 
Radiated  loss,  etc 20 


100 


The  work  done  will  be  increased  by  diminishing  the  loss  of 
heat  with  the  exhaust  gases,  but  the  loss  of  heat  to  the  cylinder 
walls  will  remain  constant.  This  assumes,  of  course,  that  the  in- 
creased time  of  expansion  is  balanced  in  loss  to  cylinder  walls  by 
more  rapid  rate  of  fall ;  if  the  piston  velocity  is  not  increased  the 
result  will  not  be  quite  so  good.  If,  for  instance,  the  piston 
velocity  is  constant,  and  the  volume  to  surface  ratio  is  constant, 
the  expansion  will  only  give  results  as  follows  : 

Work  indicated  in  cylinder  .  '  .  .  .  .  21  'o 
Heat  lost  to  cylinder  walls  and  radiated  .  .  66*5 
Heat  carried  away  by  exhaust  .  .  .  .12-5 

100 'O 

Expansion  so  arranged  as  to  be  equivalent  to  the  same  time  of 
present  piston  stroke,  0*2  seconds,  by  increasing  piston  velocity  and 
rearranging  cooling  surfaces,  will  give  25  per  cent,  of  total  heat  in 
indicated  work  :  if  surfaces  and  piston  speed  remain  unaltered,  so 
that  the  time  of  exposure  increases  in  same  ratio  as  expansion, 
then  2 1  per  cent,  only  will  be  attained.  With  proper  expansion, 
the  loss  of  heat  by  the  exhaust  gases  discharging  at  a  high  temper- 
ature may  be  greatly  diminished,  and  the  efficiency  would  be 
increased,  but  the  change  would  not  affect  the  loss  of  heat  to 
cylinder  walls  ;  it  would  even  increase  it. 


264  The  Gas  Engine 

How  can  this,  the  greatest  loss  in  the  gas  engine,  be  reduced  ? 
The  loss  depends,  as  has  already  been  stated,  upon  the  ratio  of 
surface  to  volume  of  gases  exposed  to  cooling,  upon  the  time  of 
exposure,  and  upon  the  elevation  of  the  temperature  of  the  hot 
gas  above  the  enclosing  surfaces  cooling  it. 

It  is  evident  that  as  engines  increase  in  power,  the  capacity 
of  cylinders  of  similar  proportions  increase  as  the  cube  of  the 
diameter,  while  the  area  of  the  enclosing  cold  surfaces  increases  as 
the  square  of  the  diameter.  As  engines  of  greater  and  greater 
power  are  constructed,  the  surface  exposed  in  proportion  to  volume 
becomes  less  and  less ;  the  loss  of  heat  from  this  cause  will,  there- 
fore, diminish. 

Increase  in  piston  velocity  will  also  diminish  loss,  by  diminishing 
time  of  contact  :  300  feet  per  minute  is  the  usual  speed  at  present, 
and  it  cannot  be  advantageously  increased  in  small  engines,  as  the 
reciprocations  of  the  parts  become  too  frequent  for  durability  :  but 
in  large  engines  with  diminishing  reciprocation,  the  piston  speed 
may  be  increased  to  600  feet  per  minute,  and  still  be  within  the 
limits  practised  in  steam  engines. 

Increase  in  temperature  of  cylinder  walls  is  also  advantageous 
within  certain  limits.  The  author  has  found  a  difference  of  as 
much  as  10  per  cent,  upon  the  consumption  of  gas  of  an  Otto 
engine  when  at  17°  C.,  and  so  hot  that  the  water  in  the  jacket  was 
just  short  of  boiling  96°  C.  It  is  probable  that  still  higher 
temperature  could  be  advantageously  used,  but  there  is  a  limit 
imposed  both  by  theory  and  practice. 

However,  the  cycle  could  be  modified  to  permit  the  use  of 
very  hot  walls,  enclosing  the  gases  at  500°  C. 

When  all  these  precautions  against  loss  are  practised  in  large 
engines,  and  the  heat  loss  is  greatly  reduced,  another  complication 
steps  in,  which  modifies  the  theory  of  the  engine  very  considerably. 
That  complication  is  the  property  possessed  by  all  explosive 
gaseous  mixtures  of  suppressing  part  of  their  heat-  the  phe- 
nomenon of  Dissociation,  the  '  Nachbrennen '  of  the  Germans,  or 
the  apparent  change  of  specific  heat  or  continued  combustion  of 
the  French  and  the  English. 

Although  a  gaseous  explosion  expanding  in  a  cold  cylinder 
behind  a  piston  doing  work  very  nearly  follows  the  adiabatic  line, 


The  Future  of  the  Gas  Engine  26$ 

yet  if  expanded  under  such  circumstances  that  the  loss  of  heat 
was  greatly  diminished,  it  would  no  longer  do  so. 

In  large  engines  the  expansion  curve  is  always  above  the  adia- 
batic  ;  in  small  engines  it  is  below  the  adiabatic. 

In  fig.  53,  diagram  taken  by  Professor  Thurston,  if  all  loss  of 
heat  to  the  cylinder  could  have  been  prevented,  the  expanding 
line  would  have  been  an  isothermal,  the  maximum  temperature  of 
1657°  would  have  been  sustained  to  the  end  of  the  stroke,  and  the 
actual  efficiency  of  the  diagram  would  have  been  0*40,  that  is, 
40  per  cent. 

At  the  point  7  the  temperature  would  be  1657°,  and  the  gases 
would  still  contain  60  per  cent,  of  all  the  heat  given  to  them,  and  if 
expanded  to  atmosphere  adiabatically,  the  combustion  being  sup- 
posed complete,  then  13  per  cent,  would  be  added,  making  a 
total  efficiency  of  53  per  cent. 

If  the  loss  of  heat  through  the  cylinder  could  be  totally  sup- 
pressed, the  possible  efficiency,  taking  into  consideration  the 
properties  of  explosive  gases  is  53  per  cent.  It  is  impossible  to 
completely  avoid  loss  to  the  cylinder,  but  it  will  doubtless  be 
greatly  reduced. 

The  united  effect  of  expansion,  greater  piston  speed  and  reduc- 
tion of  loss  of  heat  to  the  cylinder  by  using  hot  liners,  when  carried 
out  in  an  engine  of  considerable  power,  would  cause  the  attainment 
of  a  practical  heat  efficiency  of  at  least  40  per  cent,  and  this  with- 
out any  great  change  in  the  construction  of  gas  engines  now  made. 

Now,  how  do  these  efficiencies  compare  with  those  of  the  steam 
engine?  It  is  generally  admitted  that  the  best  steam  engines 
of  considerable  powers  and  of  the  latest  type,  when  in  ordinary 
work  do  not  give  an  efficiency  greater  than  10  per  cent.,  that  is, 
they  do  not  convert  more  than  10  per  cent,  of  the  heat  given  to 
the  boiler  in  the  form  of  fuel,  into  indicated  work.  In  small  engines 
of  such  powers  as  are  comparable  with  the  largest  gas  engines  yet 
constructed,  the  results  are  not  nearly  so  good,  an  efficiency  of 
4  per  cent,  being  a  good  result. 

The  reader  will  remember  that  the  term  efficiency,  as  used  in 
this  work  throughout,  is  defined  to  mean  the  proportion  of  heat 
converted  into  work,  to  total  heat  given  to  the  heat  engine. 

Efficiency  is  often  used  in  another  sense,  and  considerable- 


266  The  Gas  Engine 

confusion  has  arisen  because  of  its  use  in  different  senses  by  diffe- 
rent writers.  In  comparing  engines  differing  in  their  nature,  the 
only  standard  of  comparison  possible  is  the  total  heat  or  total  fuel 
given  to  each  engine,  and  the  proportion  of  total  heat  or  total  fuel 
which  that  engine  can  convert  into  work.  The  source  of  power  is 
always  combustion,  and  the  temperature  of  combustion  may  always 
be  supposed  to  be  the  superior  limit  of  temperature  whatever  the 
working  process,  whether  steam  or  air  is  the  working  fluid.  From 
the  fact  of  taking  the  total  heat  as  the  basis  of  comparison,  the 
reader  is  not  to  infer  that  it  is  possible  even  in  theory  to  convert 
all  of  it  into  work.  Professor  Osborne  Reynolds,  in  a  lecture  be- 
fore the  Institution  of  Civil  Engineers,  stated  that  this  seemed  to 
be  a  belief  popular  among  engineers  ;  the  author  does  not  think 
that  this  is  so. 

Certainly,  the  second  law  of  Thermodynamics  is  not  so  widely 
understood  among  engineers  as  it  should  be,  but  still,  few  suppose 
that  it  is  even  theoretically  possible  to  convert  all  the  heat  given 
to  an  engine  into  work. 

In  the  discussion  on  the  author's  paper  on  'The  Theory  of  the 
Gas  Engine,'  at  the  Institution  of  Civil  Engineers,  considerable 
confusion  arose  from  the  term  efficiency  being  used  in  different 
senses  by  different  speakers.  Professor  Fleeming  Jenkin  in  his 
lecture  very  clearly  defines  the  different  legitimate  uses  of  the 
term. 

Returning  to  the  comparison  of  gas  and  steam  engine  heat 
efficiency,  the  10  per  cent,  of  the  steam  engine  is  probably  very 
nearly  as  much  as  can  be  ever  attained  ;  it  may  be  exceeded  by 
using  high  pressures  and  great  expansion,  but  it  will  never  be  pos- 
sible to  attain  anything  like  20  per  cent.  The  limits  of  tempera- 
ture are  such  that  if  the  steam  cycle  were  perfect,  only  32  per  cent, 
of  the  whole  heat  could  be  converted  into  work  ;  at  the  boiler 
pressures  and  condenser  temperatures  used,  the  theoretical  effi- 
ciency of  the  steam  engine  cycle  is  within  80  per  cent,  of  the  cycle 
of  a  perfect  engine,  that  is,  the  efficiency  theoretically  possible  is 
32  x  0-8  =  25-6  per  cent.  In  an  experiment  made  by  Messrs. 
B.  Donkin  &  Co.  on  a  63  HP  compound  engine,  the  results  as 
given  by  Professor  Cotterill  in  his  work  on  the  steam  engine  are 
^s  follows : 


The  Future  of  the  Gas  Engine  267 

Per  cent. 
Absolute  efficiency       .         .        .        .         .         .     ii'i 

Efficiency  of  a  perfect  engine       .        .         .         .28-4 

Relative  efficiency        .         .        ,        .         .        .     39-1 

The  engine  received  100  heat  units  from  the  boiler  as  dry 
steam,  and  it  gave  in  units  as  indicated  work  in  the  cylinder. 
With  the  pressures  and  temperatures  given,  the  steam  engine  cycle, 
if  perfectly  carried  out,  falls  short  of  the  cycle  of  a  perfect  heat 
engine  between  the  limits,  so  that  227  per  cent  is  the  maximum 
efficiency  which  could  be  obtained,  supposing  no  other  loss  than 
that  due  to  the  imperfection  of  the  cycle.  The  cylinder  losses, 
condensation,  incomplete  expansion  and  misapplication  of  heat, 
make  the  actual,  indicated  efficiency  ii'i  per  cent.,  so  that  half 
has  gone.  The  furnace  loss  diminishes  the  absolute  efficiency  to 
9-2  per  cent,  and  it  is  extremely  improbable  that  improvement 
can  ever  increase  this  to  18  per  cent,  which  is  the  indicated 
efficiency  of  the  gas  engine  as  at  present. 

It  is  impossible  that  the  steam  engine  can  ever  offer  an  effi- 
ciency of  40  per  cent.,  which  is  quite  possible  with  the  gas  engine. 

What  remains  to  be  done,  then,  in  order  to  make  the  gas 
engine  compete  with  steam  for  really  large  powers  ?  At  present 
the  largest  gas  engines  do  not  indicate  more  than  40  HP,  and 
very  few  are  in  use  so  powerful. 

The  gas  engine,  although  superior  in  efficiency  as  a  heat 
engine  to  the  steam  engine,  is  not  superior  in  economy  except  for 
small  powers,  where  steam  engines  are  very  wasteful  and  the  cost 
of  attendance  relatively  great 

The  unit  of  heat  supplied  in  the  form  of  coal  gas  is  more 
costly  than  the  unit  of  heat  supplied  in  the  form  of  coal.  Gas 
producers  are  required  which  will  convert  the  whole  of  the  fuel 
into  gas  as  readily  as  steam  is  produced,  and  with  no  greater  loss 
of  heat  than  a  boiler  has. 

Mr.  J.  E.  Dowson's  producer  is  the  only  one  at  present  in 
existence  giving  suitable  gas,  and  it  requires  the  special  fuel 
anthracite. 

The  use  of  ordinary  fuel  has  not  yet  succeeded. 

A  good  gas  producer,  giving  gas  usable  and  free  from  tar,  is 
much  wanted. 


268  The  Gas  Engine 

But  when  all  this  is  done,  the  gas  engine  remains  in  some 
respects  inferior  to  the  steam  engine.  It  would  then  be  a  great 
advance  in  economy,  as  it  is  at  present  much  superior  as  a  heat 
engine,  or  machine  for  the  conversion  of  heat  into  work.  But 
mechanically  it  would  still  be  inferior  to  steam. 

As  a  piece  of  mechanism,  the  steam  engine  is  almost  perfect  : 
it  is  started,  stopped,  and  regulated  in  a  very  perfect  manner.  Its 
motion  is,  in  good  examples,  almost  perfectly  uniform  under 
variation  of  load,  and  but  little  fly-wheel  power  is  required,  be- 
cause there  is  little  or  no  negative  work. 

Its  motion  is  perfectly  under  control. 

The  gas  engine  itself  requires  much  improvement  in  this  re- 
spect ;  it  is  a  comparatively  inferior  machine  ;  at  best  it  receives 
only  one  impulse  every  revolution  when  at  full  power,  and  when 
under  light  loads  only  an  occasional  impulse. 

Means  must  be  found  to  make  it  double  acting,  and  to 
diminish  the  power  of  the  impulses  instead  of  diminishing  their 
frequency  for  governing. 

Means  must  also  be  found  to  start  and  stop  as  in  steam 
engines  ;  the  present  starting  gear  is  a  step  in  this  direction,  but 
requires  development. 

All  this  can  and  will  be  done;  it  is  a  matter  of  time  and 
patience.  It  can  and  will  be  made  as  mechanically  perfect  and 
controllable  as  the  steam  engine.  Flame  and  explosion,  seemingly 
so  untameable  and  destructive,  have  been  to  a  great  extent  tamed 
and  harnessed  in  present  engines.  Experience  is  growing,  by 
which  it  will  be  as  easily  and  certainly  directed  in  the  cylinder  of 
an  engine  as  steam  is  at  present.  The  furnace,  at  present  sepa- 
rated from  the  engine,  will  be  transferred  to  the  engine  itself,  and 
the  power  required  will  be  generated  as  required  for  each  stroke, 
and  the  system  of  storing  it  up  in  enormous  reservoirs — steam 
boilers — finally  abandoned. 

The  masses  of  smoke  polluting  our  atmosphere  will  be  entirely 
abolished  so  far  as  motive  power  is  concerned. 

The  author  cannot  do  better  in  conclusion  than  quote  the 
late  Professor  Fleeming  Jenkin,  expressing  his  belief  in  the  future 
of  this  form  of  motor. 

'  Since  that  is  the  case  now,  and  since  theory  shows  that  it  is 


The  Future  of  the  Gas  Engine  269 

possible  to  increase  the  efficiency  of  the  actual  gas  engine  two  or 
even  threefold,  then  the  conclusion  seems  irresistible,  that  gas 
engines  will  ultimately  supplant  the  steam  engine.  The  steam 
engine  has  been  improved  nearly  as  far  as  possible,  but  the 
internal-combustion  gas  engine  can  undoubtedly  be  greatly  im- 
proved, and  must  command  a  brilliant  future.  I  feel  it  a  very 
great  privilege  to  have  been  allowed  to  say  this  to  you,  and  I  say 
it.  with  the  strongest  personal  conviction.' 


PART    II. 

GAS   ENGINES    PRODUCED    SINCE    1886. 
CHAPTER    I. 

GAS   ENGINES   GIVING   AN    IMPULSE   FOR    EVERY   REVOLUTION. 

THE  first  part  of  this  work  was  published  in  1886,  and  the 
account  of  the  different  engines  described  is  accurate  up  to  that 
date ;  the  scientific  part  of  the  work,  dealing  with  the  thermo- 
dynamics of  the  gas  engine,  and  the  various  causes  of  loss 
operating  in  working  engines,  is  as  true  to-day  as  when  written, 
and  requires  no  modification. 

The  ten  years  elapsing  between  1886  and  the  present  year 
have-  however,  seen  many  important  changes  in  details  of  con- 
struction, and  a  considerable  advance  has  been  made  in  the 
construction  of  large  gas  engines.  Gas  producers  have  been 
more  extensively  adopted  ;  petroleum  engines  have  been  pro- 
duced which  are  practically  useful  although  not  quite  so  well 
understood  as  gas  engines  \  very  effective  and  simple  starting 
gears  have  been  invented  and  extensively  applied ;  the  slide 
valve  igniters  have  been  practically  abandoned,  and  the  hot  tube 
igniters  have  taken  their  place ;  the  compound  principle  has 
been  advanced  a  stage ;  and  generally  the  gas  engine  has  been 
made  as  reliable  in  its  action  as  any  steam  engine. 

The  Otto  patent  of  1876  (No.  2081)  expired  in  1890,  and 
this  event  has  had  a  most  important  effect  on  the  gas  engine 
from  a  commercial  point  of  view  ;  so  many  engineers  now  make 
Otto  cycle  engines  that  the  selling  price  for  any  given  power 
has  fallen  from  40  per  cent,  to  50  per  cent,  as  compared  with 
1886  prices.  So  far  this  fall  in  prices  has  had  one  good  effect, 


272  The  Gas  Engine 

and  has  greatly  increased  the  number  of  gas  engines  in  use,  by 
bringing  the  cost  within  the  means  of  many  small  manufacturers 
formerly  unable  to  stand  the  considerable  first  cost  of  a  gas 
engine. 

The  lapse  of  the  Otto  master  patent  has,  however,  had 
another  effect  which  may  prove  an  obstacle  in  the  development 
of  the  gas  engine.  In  Britain  the  Otto  cycle  engine  is  now 
practically  the  only  engine  manufactured ;  the  whole  of  the 
impulse-every-revolution  engines  have  disappeared  from  the 
market ;  many  are  still  in  successful  work,  but  their  makers 
with  wonderful  unanimity  have  ceased  their  manufacture,  and 
have  generally  taken  to  the  construction  of  Otto  engines.  At 
the  present  time  practically  the  whole  of  the  engines  manufactured 
and  offered  for  sale  in  this  country  by  engineers  are  engines 
operating  on  the  Otto  cycle,  giving  one  impulse  for  every  four 
single  strokes  of  the  piston. 

This  state  of  affairs  offers  emphatic  testimony  to  the  practical 
advantages  of  the  Otto  cycle,  and  in  the  author's  opinion  engi- 
neers are  correct  in  considering  the  Otto  cycle  as  likely  to  remain 
unrivalled  for  small  and  perhaps  moderate  power  gas  engines. 
For  really  large  engines,  however,  it  appears  to  him  that  the 
Otto  cycle  is  inherently  defective,  and  he  still  considers  impulse 
every  revolution  or  two  impulses  per  revolution  as  much  prefer- 
able, and  as  certain  to  prove  the  type  of  the  future  for  really  large 
power  engines.  It  is  therefore  much  to  be  regretted  that  for  the 
present  engineers  have  practically  ceased  their  efforts  in  the 
direction  of  more  frequent  impulses,  and  have  devoted  them- 
selves entirely  to  the  development  of  the  Otto  type. 

The  following  are  the  leading  makers  of  Otto  cycle  gas 
engines  in  Britain  : 

Messrs.  Crossley  Bros.,  Limited,  Manchester  ;  Messrs.  J.  E.  H. 
Andrew  &  Co.,  Limited,  Reddish  ;  Messrs.  T.  B.  Barker  &  Co., 
Birmingham  ;  Messrs.  Tangyes,  Limited,  Birmingham  ;  Messrs. 
Dick,  Kerr  &  Co.,  Limited,  Kilmarnock  ;  Messrs.  Robey  &  Co., 
Limited,  Lincoln  ;  Messrs.  Fielding  &  Platt,  Gloucester ;  and 
Messrs.  P.  Burt  &  Co.,  Glasgow. 

There  are  many  other  engineers  who  manufacture  good  Otto 
cycle  engines,  but  a  description  of  engines  by  several  of  these 


Gas  Engines  giving  an  Impulse  for  Every  Revolution    273 

makers  will  put  the  reader  in  full  possession  of  the  leading  points 
of  recent  gas-engine  practice.  Before  beginning  the  Otto  cycle 
engines,  however,  it  is  advisable  to  consider  shortly  the  position 
of  impulse-every-revolution  engines  from  1886. 

Atkinsoris  '  Cycle '  Gas  Engine. — The  most  important  of  the 
engines  giving  an  impulse  every  revolution  produced  since  the 
year  1886,  was  undoubtedly  the  engine  called  by  Mr.  Atkinson 
the  'Cycle.'  At  page  197  of  this  work  will  be  found  a  description 
of  Atkinson's  Differential  Gas  Engine,  in  which  a  most  ingenious 
attempt  was  made  to  obtain  greater  expansion  than  was  given  in 
Otto  engines.  To  a  certain  extent  this  attempt  was  successful, 
and  the  combustible  mixture  was  expanded  after  explosion  to  a 
volume  considerably  greater  than  the  volume  existing  before 
compression.  Considerable  economy  was  obtained  in  the  engine, 
but  certain  practical  difficulties  intervened  which  caused  Mr. 
Atkinson  to  invent  another  engine  quite  as  ingenious,  but 
having  one  piston  instead  of  two. 

The  engine  is  shown  in  longitudinal  section  at  fig.  102,  in  plan 
at  fig.  103,  and  at  fig.  104  at  i,  2,  3  and  4  are  given  the  four 
principal  positions  of  the  linkage  and  piston,  carrying  into  effect 
the  operations  of  the  engine.  The  piston  makes  two  out  and  two 
in  strokes  for  every  explosion  given,  and  in  this  feature  the  engine 
resembles  the  Otto,  but  here  the  resemblance  ends.  The  piston 
is  so  coupled  to  the  crank  shaft  that  the  whole  four  single  strokes 
are  performed  during  one  revolution  ;  and,  moreover,  the  four 
strokes  differ  in  length  and  range  in  the  cylinder,  so  that  while 
on  one  in-stroke  the  piston  proceeds  almost  entirely  to  the  end  of 
the  cylinder  to  sweep  out  practically  the  whole  of  the  products  of 
combustion,  on  the  next  in-stroke  it  stops  short  and  leaves  a  con- 
siderable compression  space  ;  on  one  out-stroke  also  a  short 
distance  is  traversed,  and  on  the  other  out-stroke  a  longer  stroke 
is  made  to  obtain  greater  expansion.  That  is,  during  the  exhaust- 
ing in-stroke  the  piston  moves  close  up  to  the  cylinder  cover  ; 
during  the  compressing  in-stroke  it  leaves  a  considerable  space  ; 
during  the  expanding  out- stroke  after  explosion  the  piston  makes 
its  longest  sweep  ;  and  during  the  charging  out-stroke  it  makes  a 
shorter  sweep. 

T 


2/4 


The  Gas  Engine 


FIG.  102. — Atkinson  Cycle  Engine  (longitudinal  section). 


FIG.  103.— Atkinson  Cycle  Engine  (plan). 


Gas  Engines  giving  an  Impulse  for  Every  Revolution    275 

By  these  variations  in  length  of  stroke  and  position  of  sweep 
in  the  cylinder,  the  piston  not  only  sweeps  out  the  whole  of  the 
products  of  combustion,  but  it  also  expands  the  burned  gases 
beyond  the  volume  existing  before  compression.  The  linkage 
invented  by  Mr.  Atkinson  to  perform  these  operations  is  ex- 
tremely simple  and  ingenious,  and  will  be  best  followed  by  an 
examination  of  the  diagrammatic  illustration  i,  2,  3  and  4  of 
fig.  104. 

The  cylinder  A  contains  the  piston  B,  which  piston  is  con- 
nected to  the  crank  c,  which  rotates  in  the  direction  of  the  arrow 
5  ;  the  connecting  rod  D  from  the  crank  c  connects  to  a  toggle 
lever  E,  pivoting  from  the  fixed  centre  6,  at  the  centre  7  ;  the 
connecting  rod  D  carries  a  short  lever  Dl  rigidly  attached  to  it 
and  carrying  a  pin  or  centre  8,  and  to  this  pin  or  centre  8  is  co"- 
nected  the  second  connecting  rod  or  toggle  link  F.  By  the 
rotation  of  the  crank  c,  the  toggle  lever  E  is  constrained  to 
oscillate  on  its  pivoting  point  or  centre  6,  between  the  limits' 
shown  by  the  dotted  lines  9  and  10.  The  centre  7  of  the  con- 
necting rod  D  and  lever  E  thus  describes  the  arc  shown  by  the 
dotted  line  between  the  lines  9  and  10,  and  if  the  rod  F  were  con- 
nected to  the  centre  7  the  piston  B  would  make  two  out  and  two 
in-strokes  for  every  revolution  of  the  crank  c,  and  the  two  strokes 
would  be  of  equal  or  unequal  length  depending  on  the  equal  or 
unequal  oscillation  of  the  toggle  lever  E  about  a  central  position 
with  regard  to  the  connecting  rod  F,  but  in  this  case  the  in-stroke 
of  the  piston  B  would  always  terminate  at  the  same  point,  and  so 
one  stroke  could  not  be  arranged  to  clear  out  the  exhaust  gases1, 
while  another  left  the  required  compression  space.  To  produce 
this  desired  variation,  Mr.  Atkinson  provides  the  short  lever  D1 
which  oscillates  about  the  centre  7,  describing  an  arc  between  the 
dotted  lines  n  and  12  about  the  centre  line  of  the  lever  E.  The 
position  of  the  centre  8  relative  to  the  centre  line  cf  E  depends  on  the 
position  of  the  crank  c  in  the  crank  circle,  and  the  angle  between 
the  lines  n  and  12  depends  upon  the  relative  length  of  the  con- 
necting rod  D,  as  compared  with  the  diameter  of  the  circle 
described  by  the  crank  c,  and  also  the  angle  between  the  lines  9 
and  10. 

In  diagram   i   (fig.    104)    the  piston    B  is  at  its  extreme  in 

T  2 


276 


The  Gas  Engine 


FlG.  104.— Atkinson  Cycle  Engine! 
(four  positions  of  linkage). 


position,  and  all  products 
of  combustion  have  been 
expeiled;  the  crank  c  ro- 
tates in  the  direction  of  the 
arrow  5,  and  in  diagram  2 
the  piston  B  has  made  its 
out  charging  stroke,  taking 
into  the  cylinder  a  charge 
of  gas  and  air  at  atmospheric 
pressure.  It  is  to  be  ob- 
served that  in  diagram  2 
the  piston  B,  although  at 
the  end  of  its  charging 
stroke,  still  remains  within 
the  cylinder  A  ;  in  diagram 
3  the  crank  c  has  still 
further  rotated,  and  now 
the  piston  B  has  attained 
the  extreme  in-end  of  its 
compression  stroke,  the 
mixed  gases  are  fully  com- 
pressed and  ready  for  ex- 
plosion, the  explosion  takes 
place  at  the  position  shown 
in  diagram  3,  and  the  crank 
c  continuing  to  rotate,  the 
parts  at  the  extreme  out- 
ward position  of  the  piston 
B  after  expanding  the  gases 
assume  the  position  of  dia- 
gram 4.  In  this  latter 
position  it  will  be  observed 
that  the  piston  B  has  tra- 
velled somewhat  out  of  the 
cylinder  A,  that  is  it  has 
made  a  longer  stroke  than 
the  compression  stroke. 
The  stroke  made  in  passing 


Gas  Engines  giving  an  Impulse  for  Every  Revolution    277 

from  the  position  of  diagram  4  to  that  of  diagram  i  is  the  longest 
of  all  strokes,  as  in  it  the  piston  passes  from  the  extreme  out- 
position  of  expansion  right  into  the  cylinder  cover,  and  sweeps 
out  all  the  products  of  combustion.  The  next  out-stroke  is 
shorter,  taking  in  the  charge  ;  the  following  in-stroke  is  shorter 
still,  compressing  the  charge  and  leaving  a  compression  space  ; 
then  follows  the  longest  out-stroke,  that  of  expanding  the  gases 
after  explosion.  A  comparison  of  diagrams  i  and  3  shows  the 
reason  of  the  difference  of  position  of  the  piston  B  ;  although  in 
both  cases  the  toggle  lever  E  is  in  practically  the  same  position, 
in  i  the  crank  c  is  on  one  side  of  the  crank  circle,  while  in  2  it  is 
on  the  other  side,  so  that  the  lever  D  is  thrown  from  the  top  of 
the  centre  line  of  the  toggle  lever  E  to  a  position  under  it,  but  the 
effect  of  the  movement  is  to  draw  the  piston  forward  from  the 
cylinder  cover.  By  studying  the  positions  of  the  lever  D  and  the 
positions  of  the  toggle  lever  E  from  the  diagrams,  the  action  will 
be  readily  followed. 

In  the  engine  rated  at  6  HP  nominal,  the  cylinder  is  9*5  ins. 
diameter,  and  the  four  successive  strokes  are  as  follows  : 

ist  (out-stroke)  Suction  of  gas  and  air  charge          .  6*33  ins. 

2nd  (in-stroke)  Compression  of  charge     .         -  -.  .  t  5-03  ins. 

3rd  (out-stroke)  Working  expansion  after  explosion  n'i3  ins. 

4th  (in-stroke)  Discharging  exhaust          .         .         .  12-43  ins. 

The  construction  of  the  6  HP  engine  is  shown  at  figs.  102  and 
103  in  longitudinal  section  and  elevation  ;  A  is  the  cylinder  ;  \\ 
the  piston  ;  c  the  crank  ;  D  the  connecting  rod  to  the  toggle  lever  ; 
E  the  toggle  lever  ;  D1  the  short  connecting  rod  lever ;  F  the  con- 
necting rod  between  the  piston  and  the  pin  8  on  the  lever  D1  ;  G  is 
the  water  jacket  surrounding  the  cylinder  and  fitted  with  the  usual 
openings  for  pipe  connections  to  the  tank ;  H  is  an  incandescent 
^igniting  tube,  open  to  the  cylinder,  and  arranged  to  operate  with- 
out timing  valve  in  a  manner  to  be,  described  later  on  ;  i  is  the 
exhaust  valve  ;  and  K  the  gas  and  air  inlet  valve  (shown  in  plan, 
fig.  103) ;  L  is  the  gas  valve.  All  three  valves  are  of  the  usual 
conical-seated  lift  type  held  on  their  seats  by  springs,  and  they  are 
operated  from  the  crank  shaft  by  cams  i1  K1,  and  rods  i2  K2,  in 
the  usual  way.  The  governor  is  indicated  at  L1,  and  it  is  of  the 
rotating  centrifugal  type  ;  it  acts  on  a  rod  connecting  between  the 


2;  8  The  Gas  Engine 

actuating  cam  and  the  gas  valve  stem  to  cause  the  end  of  the  rod  to 
be  withdrawn,  and  the  gas  valve  stem  missed,  so  leaving  the  gas 
valve  closed  for  a  stroke  or  a  number  of  strokes.  This  also  ''s  a 
common  device. 

Diagrams  and  Gas  Consumption. — A  test  of  the  first  *  Cycle  ' 
engine  constructed  was  made  in  April  1887  by  Professor  W.  C. 
Unwin,  F.R.S.,  for  the  British  Gas  Engine  Co.,  Ltd.,  the  makers 
of  the  engine  in  London. 

The  engine  was  rated  at  4  HP  nominal,  the  diameter  of  the 
cylinder  7*5  ins.  and  the  expansion  or  working  stroke  9^25  ins. 

The  leading  results  obtained  were  as  follows  : 

Indicated  Horse  Power 5  '563 

Brake  „  4'88;> 

Gas  consumed  in  one  hour    .....  100  cb.  ft. 

Gas  consumption  per  I  HP  per  hour       .         .         .  1978  cb.  ft. 

Gas  consumption  per  brake  HP  per  hour       .         .  22*50  cb.  ft. 

Efficiency  of  mechanism 87-9  per  cent. 

Heating  value  of  gas  in  Ibs.  degree  C°  per  cb.  ft. .  349'3 

Professor  Unwin  accounts  for  every  100  heat  units  used  by 
the  engine  as  follows  : 

Accounted  for  in  indicator  diagram          .         .         .         .20-62 

Given  to  jacket  water       .......     19*37 

Difference,  exhaust  gases,  radiation,  £c.          .         .         .     60-1 


An  indicator  diagram  taken  during  the  test  is  given  at  fig.  105, 
and  in  dotted  lines  on  the  same  diagram  is  one  taken  by  Dr.  Slaby 
from  a  4  HP  Otto  engine.  This  latter  diagram  was  taken  by 
Dr.  Slaby  during  a  test  referred  to  at  page  170  of  this  work. 

The  ratio  of  the  expansion  in  the  Otto  engine  was  27  as  com- 
pared with  375  in  Atkinson's  ;  that  is,  in  the  Otto  engine,  the 
volume  of  the  compression  space  being  taken  as  i,  then  the  total 
volume  behind  the  piston,  when  the  piston  was  full  out,  was 
27  volumes  ;  the  sweep  of  the  piston  was  therefore  17  times  the 
volume  of  the  compression  space  ;  in  the  Atkinson  engine,  the 
volume  of  the  compression  space  being  i,  the  volume  swept  by 


Gas  Engines  giving  an  Impulse  for  Every  Revolution    2/9 

the  piston  during  expansion  was  275  ;  the  gases  contained  in 
the  compression  space  were  thus  expanded  from  i  volume  to 
375  volumes.  In  the  author's  opinion,  Professor  Unwin's 
diagram  fig.  105  is  hardly  fair  to  the  Otto  engine,  as  it  appears 
to  somewhat  exaggerate  the  amount  of  expansion  obtained  in  the 
cycle  engine  as  compared  with  the  Otto,  and  the  diagram  should 
be  so  corrected  as  to  allow  for  the  differing  combustion  spaces. 
The  expansion,  however,  in  the  Atkinson  engine  is  doubtless  much 
greater  than  in  the  Otto,  and  accordingly  the  gases  fall  to  a 


i. 


<£ 


FIG.  105.— Atkinson  Cycle  Engine  (Prof.  Unwin's  diagram). 

pressure  of  about  15  Ibs.  per  square  inch  before  the  exhaust  valve 
is  opened. 

An  important  series  of  tests  were  made  by  judges  appointed 
by  the  Society  of  Arts,  Dr.  John  Hopkinson,  F.R.S.,  Professor 
A.  B.  W.  Kennedy,  F.R.S.,  and  Mr.  Beauchamp  Tower,  at  South 
Kensington  in  1888,  of  the  Crossley,  Griffin,  and  '  Cycle'  gas 
engines,  from  which  it  appeared  that  the  Atkinson  '  Cycle '  gave 
distinctly  the  lowest  gas  consumption.  The  principal  results 
o.btained  were  as  follows  : 


280 


The  Gas  Engine 


SOCIETY  OF  ARTS  TRIAL.— ATKINSON  ENGINE. 

Indicated  Horse  Power        ...  .11-15 

Brake  ,,  9'48 

Gas  consumed  in  cylinder  in  one  hour          .         .     209-8  cb.  ft. 
Gas  consumed  for  ignition  in  one  hour  .         4-5  cb.  It. 

Gas  consumption  per  IHP  per  hour  total     .         .     22-61  cb.  ft. 
Gas  consumption  per  brake  HP  per  hour  total    .     22-61  cb.  ft. 
Efficiency  of  mechanism       .         .         .         .         -85  per  cent. 
Heating  value  of  gas  in  Ib.  degree  C,  per  cb.  ft.     351  '6 
Revolutions  per  minute       .....     131'! 

Explosions  per  minute 121 '6 

Mean  initial  pressure,  above  atmospheric   .         .     166  Ibs.  per  sq.  in. 

Mean  effective  pressure 46-07  Ibs.  per  sq.  in. 

Cooling  water  per  hour       .....     680  Ibs. 
Rise  of  temperature  cooling  water      .         .         .50°  F. 

The  engine  was  rated  at  6  HP  nominal  ;  the  cylinder  was 
9-5  inches  diameter  ;  suction  stroke  6-33  inches  ;  compression 
stroke  5*03  inches  ;  working  or  expansion  stroke  ii'i3  inches; 
and  exhaust  stroke  i2'43  inches. 

The  test  giving  these  figures  was  of  6  hours'  duration,  and 
the  engine  was  continually  loaded  to  full  power  ;  indicator  dia- 
grams were  taken  every  15  minutes,  and  diagrams  were  also 

taken  with  light  springs  to  find 

MOM  Pressure         46  Aj      the  power  absorbed  in  the  pump- 
Revotutions  per  mm   130  50  .  —.r 

Explosions  .    „     no  71      mg  and  exhausting  strokes,     r  ig. 
/   H.P  U-Q9  *     .  ,      .& 

106   is  a  diagram  taken    during 

this   trial,    and  the  leading  par- 
ticulars are  marked  upon  it. 

Fig.  107  shows  an  ideal  dia- 
FIG.  1 06.—  Atkinson  Cycle  Engine    gyam  superposed  upon  an  actual 
(Society  of  Arts  diagram).  diagram;    the   ideal   diagram    is 

the  one  assumed  by  the  judges  in 

the  Society  of  Arts  trial  as  fairly  corresponding  with  the  actual 
conditions,  lines  have  been  straightened  out,  and  curves  made 
to  follow  a  different  law  in  order  to  obtain  approximately  correct 
figures  for  temperatures  and  heat  volumes.  Standard  points 
A,  B,  c,  D,  E,  F,  and  G  have  been  taken,  and  the  volumes 
existing  behind  the  piston  accurately  measured  at  the  various 
points.  The  point  A,  for  example,  represents  the  farthest  in 
point  when  the  piston  is  full  back,  discharging  the  products  of 


Gas  Engines  giving  an  Impulse  for  Every  Revolution    281 

combustion.  The  piston  moves  out  from  A  to  B,  taking  in  the 
charge  of  gas  and  air  ;  the  piston  then  returns  from  B  to  c,  com- 
pressing the  charge  to  the  pressure  and  volume  indicated.  The 
explosion  then  occurs,  and  during  the*  rise  of  pressure  and  tem- 
perature the  piston  is  supposed  to  be  stationary,  that  is  the  volume 
behind  the  piston  is  the  same  when  the  pressure  attains  its 
maximum  as  indicated  at  D  as  at  the  point  c,  so  that  the  heat 
added  by  the  explosion  is  added  when  the  gases  are  at  constant 
volume  ;  from  D  to  E  the 
piston  is  supposed  to  move 
out  while  the  pressure  remains 
constant,  that  is  the  heat  added 
from  D  to  E  is  added  at  con- 
stant pressure.  The  hot  gases 
are  supposed  to  expand  from 
E  to  F,  following  truly  a  de- 
finite curve  in  which  pv^  = 
constant.  In  the  diagram  n 
is  taken  as  1*264,  and  the 
curve  E  F  has  the  equation 
/7;1'264  =  constant. 

The  value  of  n  for  the 
compression  curve  is  1*205, 
and  assuming  the  specific  heat 
of  the  charge  the  same  as  that 


0-1  0-2       03   •    0-+ 

ATKINSON   ENGINE 


0-5  Cub*  ft 


FIG.  107. — Atkinson  Cycle  Engine 
(Society  of  Arts  actual  and  ideal 
diagram). 


of   air,    which   assumption   is 

very  nearly  true,  then  the  value 

of  n    should   be   1-408;    the 

curve  of  compression  in   this 

diagram  is  therefore  below  the  adiabatic,  and  the  charge  is  losing 

heat  to  the  sides  of  the  cylinder  during  compression. 

The  value  of  n  for  the  expansion  line  E  F  is  1-264,  which  proves 
the  curve  to  be  much  natter  than  would  have  been  given  by  the 
adiabatic  expansion  of  a  volume  of  air  heated  to  the  maximum 
temperature  at  E.  The  ratio  of  the  specific  heats  of  the  expand- 
ing charge  at  constant  pressure  and  constant  volume  has  been 
calculated  by  the  judges  as  1*376  on  the  assumption  of  the  pre- 
sence in  the  charge  of  the  products  of.  complete  combustion. 


282 


The  Gas  Engine 


This  in  the  author's  opinion  is  a  quite  erroneous  assumption,  as 
only  about  one-half  of  the  total  heat  of  the  gas  present  is  accounted 
for  by  the  maximum  temperature,  so  that  the  specific  heat  could 
not  change  to  the  extent  assumed  ;  the  value  of  «,  however,  for 
the  expanding  charge  is  somewhere  between  1-376  and  1-408,  so 
that  the  error  introduced  is  not  great. 

The  following  table  gives  the  pressure,  volumes,  and  tem- 
perature at  the  various  points  of  the  ideal  diagram,  fig.  107  : 


Press  a  re, 
Ibs.  persq.  in.  absolute 

Volume 
in  cub.  feet 

Temperature, 
degrees  C. 

A             14-87 

0*064 

_ 

B             14-87 

0-324 

46-6  C. 

c        5030 

o'nS 

126-4  C. 

D          ido'QO 

0-118 

1182-5  C. 

E          180-90 

o"i35 

1388  i  C. 

F           29-00 

0'57S 

849-2  C. 

G           14-87 

0-575 

849-2  C. 

The  report  gives  full  calculations  of  heating .  value  of  the  gas 
used,  specific  heat  of  products  of  combustion,  and  many  other 
details  ;  several  of  these  matters  will  be  more  fully  discussed  later 
on,  in  comparing  the  results  obtained  from  different  engines. 

It  is  desirable  to  note  here,  however,  that  the  ratio  of  air  to 
gas  entering  the  cylinder  is  calculated  as  i  volume  gas  to 
9-33  volumes  of  air.  It  is  unfortunate  that  the  ratio  was  not 
determined  by  independent  measurement  of  both  gas  and  air  by 
separate  meters,  as  was  done  in  Professor  R.  H.  Thurston's 
American  test,  described  on  page  175  of  this  work.  Comparing 
the  proportions  of  coal  gas  and  air  plus  other  gases  present,  it 
is  interesting  to  note  that  in  Thurston's  experiments  the  entering 
charge  contained  i  volume  of  gas  to  7  volumes  of  air,  but  when 
mixed  with  the  products  of  combustion  in  the  compression  space 
the  average  composition  was  i  volume  coal  gas  to  9-1  volumes  of 
other  gases.  The  composition  of  the  mixture  in  the  two  cases 
thus  appears  to  be  practically  the  same.  In  the  Otto  engine, 
however,  the  temperature  of  the  charge  was  much  higher  before 
compression  than  in  the  Atkinson  engine,  as  was  also  the  tern- 


Gas  Engines  giving  an  Impulse  for  Every  Revolution    283 

perature  of  compression ;  the  maximum  temperature  of  the  ex- 
plosion would  appear  to  be  higher  in  consequence. 

The  report  gives  the  heat  account  of  the  foregoing  test  as 
follows  : 

Per  cent. 
Heat  turned  into  work  as  shown  by  indicator  diagrams  .         .       22  '8 

Heat  rejected  in  jacket  water 27-0 

Heat  rejected  in  exhaust,  lost  by  imperfect  combustion,  and 

otherwise  unaccounted  for 50*2 


This  gas  consumption  of  19*22  cub.  ft.  per  IHP  per  hour, 
giving  an  efficiency  of  22*8  per  cent,  was  the  best  result  so  far  as 
economy  was  concerned  up  to  the  date  of  the  trial,  September 
1888. 

General  Remarks. — The  Atkinson  'Cycle'  engine  was  manu- 
factured and  sold  by  the  British  Gas  Engine  Company,  London, 
from  1887  to  the  beginning  of  1893,  and  during  that  period  the 
author  is  informed  that  somewhat  over  1,000  gas  engines  were 
sold  ;  the  engine,  however,  notwithstanding  the  great  ingenuity 
of  its  construction  and  its  unrivalled  economy  of  gas  consump- 
tion, never  became  really  popular.  Difficulties  were  experienced 
with  the  linkage,  which  had  at  least  five  working  pins  as  compared 
with  the  two  pins  of  the  ordinary  connecting  rod,  and  these  diffi- 
culties ultimately  led  the  inventor  to  return  to  an  engine  of  less 
uncommon  construction,  having  only  the  ordinary  crank  and 
connecting  rod. 

Mr.  Atkinson,  however,  in  his  '  Cycle  '  engine  proved  absolutely 
the  possibility  of  obtaining  great  economy  in  gas  consumption  by 
expanding  the  gases  after  explosion  to  a  volume  much  greater 
than  existed  before  compression.  By  his  ingenious  linkage  he 
caused  one  piston  to  perform  four  strokes  within  one  revolution 
of  the  crank  shaft ;  he  also  proved  conclusively  a  point  for  which 
the  present  author  has  long  contended — namely,  that  better 
results  are  to  be  obtained  in  a  gas  engine  by  expelling  the  whole 
of  the  products  of  combustion  from  the  cylinder  than  by  retaining 
them. 

The  *  Cycle '  engine  has  a  very  high  piston  speed  for  a  given 
number  of  revolutions  of  the  crank  shaft,  as  each  complete  stroke 


284  The  Gas  Engine 

of  the  piston  was  accomplished  in  about  one  quarter  revolution, 
as  will  be  clearly  seen  by  inspecting  the  diagram,  fig.  104.  This 
high  piston  speed,  although  advantageous  so  far  as  gas  consump- 
tion was  concerned,  must  have  been  detrimental  to  the  smooth 
and  long-continued  satisfactory  working  of  the  engine,  as  the 
movements  of  the  piston  rods  and  links  were  of  a  kind  which 
could  not  be  conveniently  balanced. 

The  engine  ^was  made  in  sizes  up  to  about  30  HP  brake,  and 
the' author  understands  that  one  100  HP  engine  was  constructed, 
but  he  is  informed  that  this  size  was  never  placed  on  the  market. 

Atkinson's  '  Utilite'  Gas  Engine.— This  engine  was  invented 
by  Mr.  Atkinson  with  the  object  of  retaining  all  the  economy  of 
the  '  Cycle '  gas  engine,  while  returning  to  the  ordinary  mechanical 
arrangement  of  piston,  crank,  and  connecting  rod,  which  has  had 
the  sanction  of  engineers  and  the  public,  inasmuch  as  it  is  prac- 
tically the  only  construction  adopted  in  steam  engines. 

The  linkage  of  the  *  Cycle '  engine,  although  most  admirable 
from  an  experimental  point  of  view,  was  not  such  as  an  engineer 
would  care  to  adopt  in  a  high-speed  or  even  a  high-power  engine, 
and  although  it  served  its  purpose  by  proving  to  demonstration 
many  interesting  points,  yet  the  present  author  was  much  pleased 
to  see  Mr.  Atkinson  depart  from  it. 

The  '  Utilite '  engine  never  attained  any  real  commercial  im- 
portance, as  the  British  Gas  Engine  Company  gave  up  business 
shortly  after  they  had  begun  its  manufacture.  The  Otto  cycle 
had  just  then  taken  so  firm  a  hold  upon  the  public,  that  it 
appeared  useless  to  sue  for  popular  favour  with  any  impulse-every- 
revolution  engine,  however  good. 

The  engine  is  of  the  greatest  interest  to  engineers,  however,  as 
it  proves  how  great  economy  can  be  obtained  with  an  impuise- 
every-revolution  engine. 

The  'Utilite  '  engine  resembles  in  many  points  the  Clerk  and 
Robson  engines.  One  side  of  the  piston  operates  as  a  pump  and 
pumps  air  into  a  chamber  at  low  pressure,  from  which  it  flows 
through  a  valve  into  the  power  side  of  the  cylinder,  and  displaces 
the  exhaust  gases  before  it  through  a  port  or  ports  uncovered  by 
the  forward  movement  of  the  piston.  The  cylinder  thus  contains 


Gas  Engines  giving  an  Impulse  for  Every  Revolution    285 

a  quantity  of  air,  which  is  compressed  by  the  piston  on  its  return 
stroke,  and  charged  during  compression  with  a  charge  of  gas  and 
air  mixture,  the  gas,  however,  in  the  mixture  being  present  in 
proportion  too  great  to  be  explosive. 

The  trunk  piston  operates  in  the  cylinder  connected  to  the 
crank  shaft  by  the  connecting  rod.  The  whole  front  of  the 
cylinder  and  the  rod  and  crank  shaft  are  inclosed  within  a  casing, 
and  a  back  cover  is  arranged  to  contain  the  compression  or  ex- 
plosion space.  A  chamber  or  casing  connects  by  a  pipe  with 
an  automatic  inlet  valve,  and  another  automatic  inlet  valve  admits 
air  to  the  casing  or  chamber.  A  pump  is  operated  by  an  eccentric 
on  the  crank  shaft,  and  it  takes  in  a  charge  of  gas  and  air  by  way 
of  a  valve  and  the  gas  cock,  and  discharges  the  charge  at  the 
proper  time  by  way  of  the  valve.  The  piston  overruns  the  exhaust 
port  at  about  half-forward  stroke,  and  the  port  is  controlled  by  a 
piston  valve,  so  that,  although  the  piston  uncovers  the  exhaust 
port  at  mid-stroke,  yet  the  exhaust  gases  are  not  discharged  to 
the  atmosphere  till  the  exhaust  valve  is  opened  at  the  termination 
of  the  out -stroke. 

The  action  of  the  engine  is  as  follows  :  On  the  in-stroke  the 
piston  draws  into  the  chamber  a  charge  of  pure  air  by  way  of  the  air 
valve,  and  on  the  out-stroke  it  compresses  this  charge  to  a  pressure 
of  about  15  Ibs.  per  square  inch.  When  the  piston  is  full  forward, 
then  the  exhaust  valve  is  opened,  and  the  pressure  within  the 
working  cylinder  falls  to  atmosphere  and  the  pressure  in  the 
chamber  lifts  the  charge  valve,  and  air  rushes  by  way  of  a  pipe 
through  the  charge  valve  and  enters  the  cylinder,  clearing  before 
it  the  exhaust  gases  through  the  exhaust  port  and  valve,  which  is 
then  open.  The  piston  then  returns,  discharging  the  rest  of  the 
exhaust  gases  through  the  port  until  the  piston  crosses  that  port, 
when  it  begins  to  compress  the  air  charge.  Just  as  the  port  is 
closed,  the  gas  and  air  pump  begins  to  discharge  its  contents,  a 
mixture  of  air  and  gas,  into  the  combustion  space  of  the  cylinder 
by  way  of  the  gas  and  air  valve.  The  gas  and  air  mixture  in  the 
pump  has  too  little  air  to  make  the  charge  explosive,  and  so  it  is 
impossible  for  the  mixture  to  ignite  in  the  pump.  The  gas  being 
already  mixed  with  air  only  requires  the  addition  of  a  further 
quantity  to  become  explosive,  so  that  by  the  time  the'  charge  is 


286  The  Gas  Engine 

compressed  the  gas  is  almost  uniformly  mixed  with  the  air,  and 
is  in  a  state  to  produce  a  powerful  explosion.  The  mixture 
is  expanded  by  this  arrangement  to  a  volume  after  explosion 
and  expansion  much  greater  than  the  volume  existing  before 
compression,  and  so  considerable  advantage  is  obtained  in 
economy. 

The  cycle  of  operation  of  this  engine  is  very  similar  to  that  of 
previous  engines,  but  Mr.  Atkinson,  by  his  thorough  knowledge 
of  gas  engine  detail,  has  obtained  results,  he  informed  the  author, 
which  have  surpassed  those  previously  obtained  with  the  cycle 
engine.  The  author  regrets  that  he  has  been  unable  to  obtain 
authenticated  tests  and  diagrams  of  this  engine. 

Other  Impulse- Every -Revolution  Engines. — The  other  impulse- 
every-revolution  engines  which  have  appeared  since  1886  are  : 
The  Campbell  Gas  Engine,  manufactured  by  the  Campbell  Gas 
Engine  Co.,  Engineers,  Halifax ;  the  Midland  Gas  Engine, 
made  by  Messrs.  John  Taylor  &  Co.,  Nottingham  ;  the  Trent 
Gas  Engine,  manufactured  by  the  Trent  Gas  Engine  Co., 
Nottingham;  the  Day  Gas  Engine,  constructed  by  Messrs. 
Day  &  Co.,  of  Bath  ;  and  the  Fawcett  Engine,  constructed  by 
Messrs.  Fawcett,  Preston  &  Co.,  Liverpool. 

The  '  Campbell  Gas  Engine'  follows,  the  cycle  of  operations 
first  adopted  by  Clerk,  and  described  at  page  184  of  this  work. 
It  has  two  cylinders,  respectively  pump  and  motor,  driven  from 
cranks  placed  at  almost  right  angles  to  each  other,  the  pump 
crank  leading.  The  pump  takes  in  a  charge  of  gas  and  air,  and 
the  motor  piston  overruns  a  port  in  the  side  of  the  cylinder  at 
the  out-end  of  its  stroke  to  discharge  the  exhaust  gases.  When 
the  pressure  in  the  motor  cylinder  has  fallen  to  atmosphere,  the 
pump  forces  its  charge  into  the  back  cover  of  the  motor  cylinder 
through  a  check  valve,  displacing  before  it  the  products  of  com- 
bustion through  an  exhaust  port ;  the  motor  piston  then  returns, 
compressing  the  contents  of  the  cylinder  into  the  compression 
space.  The  charge  is  then  fired  and  the  piston  performs  its 
working  stroke.  This  is  the  Clerk  cycle. 

The  Campbell  engine,  however,  differs  in  detail  from  the 
Clerk  engine  to  some  extent. 


Gas  Engines  giving  an  Impulse  for  Every  Revolution    287 

A  hot  tube  igniter  is  used,  and  a  vibrating  pendulum  governor 
has  been  applied. 

The  Midland  Gas  Engine  also  operates  on  the  Clerk  cycle. 
An  ignition  tube  is  used,  and  governing  is  performed  by  centri- 
fugal governor. 

The  Trent  Gas  Engine  is  the  invention  of  Mr.  Richard  Simon 
of  Nottingham,  and  in  it  a  trunk  piston  of  two  diameters  is 
caused  to  perform  the  combined  operations  of  working  and 
pump  pistons.  Fig.  no  is  a  vertical  section  through  the  com- 
bustion or  compression  space,  which  in  this  engine  is  separate 
from  the  cylinder  proper. 


FIG.  108.— Trent  Gas  Engine  (vertical  section  of  cylinder). 

Fig.  1 08  is  a  vertical  section  through  the  cylinder  ;  fig.  109  is 
a  horizontal  section  also  through  the  cylinder,  showing  cylinder 
and  combustion  space  with  the  piston  removed  ;  and  fig.  no  is  a 
vertical  section  through  the  combustion  space.  The  cylinder 
has  two  diameters  A  and  c,  and  in  it  fits  a  trunk  piston  B  D  ; 
the  smaller  diameter  B  forms  the  motor  or  working  piston,  and 
the  larger  diameter  D  forms  the  pump  piston  ;  the  pump  cylinder 
being  formed  by  the  annulus  around  the  trunk  piston  B.  Both 
pistons  B  and  D  are  thus  operated  together  from  a  crank  shaft  by 
means  of  one  connecting  rod.  M  is  the  explosion  chamber,  and 
there  are  three  main  valves  ;  E  the  inlet  valve  to  the  pump;  o  the 


288 


The  Gas  Engine 


discharge  valve  from  the  pump  to  the  compression  space  M  ;  and 
R  the  exhaust  valve,     s  is  the  timing  valve  opening  to  the  hot 


H 


FIG.  109 — Trent  Gas  Engine  (horizontal  section  of  cylinder). 


FIG.  no. — Trent  Gas  Engine  (vertical  section  through  combustion  space). 

tube.      When  the  piston  B  D  makes  its  out-stroke,  gas  and  air 
mixture  is  drawn  into  the  annular  space  surrounding  the  trunk 


Gas  Engines  giving  an  Impulse  for  Every  Revolution    289 

piston  B  through  the  charge  inlet  valve  E.  On  the  in- stroke  (the 
valve  being  closed  mechanically)  the  mixture  -  of  gas  and  air  is 
forced  from  the  pump  cylinder  through  the  valve  o,  also  operated 
mechanically  into  the  combustion  chamber  M,  and  partly  into  the 
cylinder  A,  where  it  assists  to  displace  the  exhaust  gases  from  the 
cylinder  through  the  exhaust  valve  R.  The  horizontal  rib  or  par- 
tition H  prevents  the  direct  flow  of  the  entering  charge  to  the 
exhaust  valve  R.  At  a  certain  point  of  the  return  stroke,  so 
arranged  as  to  prevent  or  minimise  loss  of  charge  by  way  of  the 
exhaust  valve  R  with  the  exhaust  gases,  the  exhaust  valve  is  closed 
and  the  pump  piston  continues  to  force  mixture  into  the  space  M 
while  the  piston  B  compresses  the  charge  in  the  cylinder  ;  both 
pistons  B  D  thus  compress  the  charge,  and  at  the  in-end  of  the 
stroke,  just  after  the  valve  o  has  been  closed,  the  valve  s  is 
opened  and  the  compressed  charge  is  fired.  The  piston  is  forced 
out  under  the  resulting  pressure  ;  the  return  stroke  is  performed 
by  the  energy  of  the  fly  wheel. 

Diagrams  and  Gas  Consumption.—  From  tests  published  by 
the  Trent  Gas  Engine  Co.  as  made  by  Mr.  F.  L.  Guilford,  of 
Messrs.  G.  R.  Cowen  &  Co.,  Engineers,  Nottingham,  it  appears 


FlG.  in. Trent  Gas  Engine  (diagram  from  power  cylinder). 

that  an  engine  rated  at  4  HP  nominal  gave  10-2  IHP  at  174 
revolutions,  but  the  brake  HP  was  only  6*4  horse.  The  gas 
consumption  was  180  ft.  per  hour. 

The  enormous  difference  between  the  brake  power  and  the 
indicated  appears  to  the  author  to  point  to  an  omission  on  the 
part  of  the  experimenter  ;  the  mechanical  efficiency  could  not 
have  been  so  low  as  63  per  cent. ;  the  pump  diagram  cannot  have 
been  deducted  from  the  motor  diagram. 

TT 


290  The  Gas  Engine 

Fig.  in  is  a  diagram  taken  from  the  power  cylinder  of  a 
4  HP  engine  ;  it  shows  a  compression  pressure  of  36  Ibs.  per 
square  inch  above  atmosphere,  with  a  maximum  pressure  after 
ignition  of  only  84  Ibs.  above  atmosphere.  The  gases  are  ex- 
panded down  to  about  15  Ibs.  per  square  inch  before  discharge. 
This  diagram  proves  conclusively  that  a  large  proportion  of 
exhaust  gases  remained  in  the  engine  cylinder  unexpelled.  The 
rapidity  of  the  ignition  also  shows  that  the  combustion  space  M 
was  filled  with  rich  mixture. 

The  average  available  pressure  cannot  be  obtained  from  this 
diagram  in  the  absence  of  the  pump  diagram. 

General  Remarks. — This  type  of  engine  has  very  grave  dis- 
advantages, low  average  available  pressure,  large  cooling  surfaces, 
large  volumes  of  exhaust  products  remaining  in  the  charge,  and 
consequent  liability  to  back  ignition  if  any  attempt  is  made  to  use 
high  compression  ;  from  these  difficulties  it  follows  that  no  great 
economy  in  gas  consumption  can  be  obtained. 

The  engine  was  manufactured  for  some  years,  but  in  1894  the 
Company  ceased  business,  and  the  engine  does  not  now  appear  to 
be  manufactured. 

The  Day  Gas  Engine. — This  engine  uses  the  same  cycle  of 
operations  for  charging  the  working  cylinder  as  was  adopted  in 
the  Tangye-Robson  gas  engine,  and  also  in  the  Stockport  engine, 
described  in  pages  195  and  197  of  this  work,  but  the  inventor  in- 
geniously dispenses  with  all  valves  and  valve  gear  such  as  cams  or 
eccentrics. 

The  engine  in  one  form  may.be  described  as  valveless,  and  its 
only  moving  parts  are,  piston,  connecting  rod  and  crank  shaft  ; 
there  is  absolutely  no  valve  used  except  a  governor  valve.  Fig. 
112  is  a  sectional  elevation  of  one  form  of  the  engine,  which  is  of 
the  vertical  inverted  cylinder  class,  having  the  power  cylinder  A 
overhead. 

The  piston  B  operates  the  crank  shaft  D  by  means  of  the  piston 
rod  c.  The  crank  shaft  operates  in  a  closed  chamber  E,  which 
chamber  serves  as  a  reservoir  for  gas  and  air  mixture.  Three 
ports  are  arranged  in  the  side  of  the  cylinder  respectively,  F,  G,  H  ; 


Gas  Engines  giving  an  Impulse  for  Every  Revolution    29 1 

F  is  the  charge  inlet  port  admitting  the  charge  to  the  cylinder,  G 
is  the  exhaust  port  allowing  the  discharge  of  the  exhaust  gases 
from  the  cylinder,  and  H  is  the  air  inlet  port  to  permit  of  the 
admission  of  air  from  the  external  atmosphere.  The  charge  inlet 
port  F  communicates  with  the  charge  chamber  E,  and  opens  to  the 


FIG.  112. — Day  Gas  Engine  (vertical  section). 

cylinder  A  opposed  by  the  lip  or  projection  i  on  the  piston  B.  The 
exhaust  port  G  connects  by  the  pipe  G1  to  the  exhaust  chamber 
G2  of  usual  construction,  and  the  chamber  G2  discharges  to  the 
atmosphere  by  the  pipe  G3.  The  air  inlet  port  H  connects  by 
pipe  H1  to  the  base  of  the  engine  K,  so  as  to  quieten  the  air  inlet. 
The  action  is  as  follows.  On  the  up-stroke  of  the  piston  B  the 

U  2 


292  The  Gas  Engine 

pressure  of  the  gases  in  the  chamber  E  is  reduced  to  about  3  or 
4  Ibs.  below  atmosphere  ;  at  or  near  the  end  of  the  up-stroke  the 
lower  edge  of  the  piston  uncovers  the  air  inlet  port  H,  and  air 
rushes  into  the  chamber  to  bring  the  pressure  up  to  atmosphere  ; 
gas  is  also  admitted 'from  the  separate  governor .  valve  referred  to, 
so  that  the  chamber  E  becomes  charged  with  a  mixture  of  gas  and 
air.  On  the  down-stroke  of  the  piston  B  the  contents  of  the 
chamber  E  are  compressed  to  3  or  4  Ibs.  above  atmosphere,  and  at 
the  termination  of  the  down -stroke  the  port  F  is  uncovered  as 
shown  in  fig.  112.  The  exhaust  port  G  has  been  crossed  by  the 
piston  B  somewhat  earlier  in  the  down-stroke,  sufficiently  early  to 
allow  the  hot  gases  from  the  previous  explosion  to  discharge  to 
atmospheric  pressure  before  the  port  F  is  opened.  The  charge 
then  flows  from  the  port  F  under  slight  pressure,  strikes  against 
the  lip  or  baffle  plate  or  projection  i,  and  is  deflected  as  shown  by 

the  arrows  so  that  it  flows 
in  a  stream  to  the  end  of 
the  cylinder,  then  turns  and 
fills  the  cylinder,  expelling 
the  exhaust  gases  by  the 
port  F.  The  piston  B  then 
returns  on  its  up  stroke,  and 
FIG.  1 13. —Day  Gas  Engine  (diagram).  compresses  the  charge  into 

a  space  at  the  end  of  the 

cylinder  to  a  pressure  of  about  50  Ibs.  per  square  inch  above 
atmosphere.  The  hot  tube  L  then  ignites  the  compressed  charge, 
timing  the  explosion  by  the  position  of  the  incandescent  part  in 
a  manner  which  will  be  explained  more  fully  later  on.  The  piston 
then  makes  its  downward  stroke  under  the  pressure  of  the  ex- 
plosion. By  these  operations  an  impulse  is  obtained  at  every 
revolution,  as  in  the  Clerk,  Robson,  and  Stockport  engines. 

Loss  of  power  is  caused  by  the  absence  of  an  inlet  suction 

.valve  to  the  space  E,  and  in  later  engines  a  suction  valve  is  provided. 

This  Day  engine  has  the  peculiarity,  that  it   can  be  run  in 

either  direction;  this  is  possible  because  of  the  absence  of  timing 

valves  or  valve  gear  operated  from  the  crank  shaft. 

Diagrams  and  Gas  Consumption, — Fig,   113  is  an  indicator 


Gas  Engines  giving  an  .Impulse  for  Every  Revolution    293 

diagram  from  this  type  of  engine  rated  at  i  HP  nominal.  The 
diagram  shows  an  indicated  power  of  3*3  horse  at  180  revolu- 
tions per  minute  ;  the  cylinder  is  4-5  ins.  diameter  and  7^  ins. 
stroke.  The  author  has  not  obtained  the  gas  consumption,  but 
this  seems  no  good  reason  why  the  results  should  be  better  than 
those  obtained  with  Tangyes'  Robson  gas  engine.  That  engine 
gave  for  the  small  powers  a  gas  consumption  of  40  cubic  feet  per 
brake  HP  with  an  average  available  pressure  of  about  45  Ibs.  per 
square  inch.  The  diagram  given  shows  an  average  pressure  of 
about  45  Ibs.  per  square  inch,  and  is  probably  lower,  as  allowance 
should  be  made  for  the  work  of  charging. 

General  Remarks. — This  engine  appears  to  be  the  only  remain- 
ing impulse-every-revolution  engine  now  in  the  market  in  this 
country,  and  Messrs.  Day  &  Co.  are  to  be  congratulated  on  their 
courage  in  adhering  to  the  impulse-every-revolution  type,  and 
withstanding  the  temptation  to  desert  and  join  the  makers  of  Otto 
cycle  engines. 

The  author  wishes  Messrs.  Day  &  Co.  every  success,  but  he  is 
of  opinion  that  further  modification  is  required  if  results  are  to  be 
obtained  superior  to  the  older  Clerk,  Robson,  and  Stockport 
engines. 

The  Fawcett  Gas  Engine  was  manufactured  by  Messrs. 
Fawcett,  Preston  &  Co.,  of  Liverpool,  and  gave  very  fair  results  ; 
it  does  not  now,  however,  occupy  any  prominent  position  in  the 
market.  It  is  the  invention  of  Mr.  Beechy,  and  like  the  Clerk, 
Robson,  and  Stockport  engines,  it  gives  an  explosion  impulse  at 
every  revolution  of  the  crank  shaft. 

Fig.  114  is  a  sectional  elevation  of  the  engine  ;  fig.  115  is  a 
sectional  plan  of  explosion  chamber  and  valves. 

The  motor  cylinder  A  is  horizontal,  and  under  it  is  arranged 
the  pump  cylinder  p,  inclined  towards  the  crank  centre.  The 
motor  piston  A1  connects  to  the  crank  pin  c  by  the  connecting 
rod  D,  and  the  pump  piston  B1  connects  to  a  pin  carried  by  the 
connecting  rod  D  by  the  lower  connecting  rod  E.  The  effect  so  far 
as  the  movement  of  the  piston  B1  is  concerned  is  practically  the 
same  as  if  the  rod  E  were  also  connected  to  the  crank  pin  c.  The 


294 


The  Gas  Engine 


piston  B1  thus  reaches  the  in-end  of  its  stroke  a  little  before  the 
piston  A1,  when  the  engine  rotates  in  the  direction  of  the  arrow 
shown  in  fig.  114.  The  piston  valve  F,  fig.  115,  is  operated  from 
the  crank  shaft  by  an  eccentric,  and  it  serves  to  control  the 
admission  of  gas  and  air  to  the  pump  cylinder  B,  and  the  dis- 
charge from  the  said  cylinder  to  the  motor  cylinder  A  ;  it  also 
controls  the  admission  of  the  compressed  charge  to  the  igniting 
tube  K.  A  conical  seat  valve  G,  shown  in  dotted  lines  at  fig.  114, 
controls  the  exhaust  port  H  placed  about  the  middle  of  the 


FIG.  114. — Fawcett  Gas  Engine  (vertical  section). 

cylinder,  and  the  valve  is  actuated  by  a  bell-crank  lever  i  from  a 
cam  or  eccentric  on  the  crank  shaft.  The  action  is  as  follows  : 
The  piston  valve  F  uncovers  the  port  L  leading  by  the  passage  L1 
to  the  pump  cylinder,  the  pump  piston  B1  then  moves  forward 
drawing  in  a  charge  of  gas  and  air,  air  by  way  of  the  pipe  M,  and 
gas  by  way  of  the  annular  port  N,  and  the  perforations  or  holes  N1. 
When  the  pump  piston  has  completed  its  outstroke  the  piston 
valve  F  closes  the  port  L,  and  opens  by  way  of  the  annular  space 
between  the  two  piston  ends  of  the  valve  to  the  port  o,  which 
port  communicates  with  the  combustion  space  A2  and  cylinder  A. 


Gas  Engines  giving  an  Impulse  for  Every  Revolution    295 

The  piston  A1  is  then  on  its  instroke,  together  with  the  piston  BI, 
and  the  exhaust  valve  G  is  held  open  so  that  the  exhaust  gases 
discharge  into  the  atmosphere,  and  some  of  the  charge  enters 
from  the  pump  and  assists  to  displace  them.  When  the  piston  A1 
has  crossed  the  exhaust  port  H,  the  greater  part  of  the  burned 
gases  have  been  discharged,  and  part  of  the  pump  charge  has 


JV 


FIG.  115.  — Fawcett  Gas  Engine  (sectional  plan  of  combustion  chamber). 

been  forced  from  the  cylinder  B  through  the  passage  L1  port  L,  and 
port  o  into  the  space  A2  ;  the  continued  movement  of  the  piston 
forces  a  further  part  of  the  charge  into  the  working  cylinder  while 
compression  is  being  caused  by  both  pistons.  When  the  piston  B.1 
arrives  at  the  in- end  of  its  stroke  the  piston  valve  moves  to  close 
the  port  L,  as  shown  in  fig.  115,  and  the  piston  A1  further  com- 
presses the  charge.  The  continued  movement  of  the  piston 
valve  F  opens  the  incandescent  tube  K,  and  ignition  takes  place, 


296  The  Gas  Engine 

driving  the  piston  A1  on  its  working  stroke.  The  charge  is  ex- 
panded to  the  end  of  the  stroke,  and  the  exhaust  valve  is  opened 
for  the  return.  By  this  arrangement  an  impulse  is  secured  at  every 
revolution  of  the  engine. 

Diagrams  and  Gas  Consumption.— Experiments  on  the  engine 
were  made  by  Mr.  T.  L.  Miller  in  1890,  from  which  it  appears 
that  in  an  engine  indicating  n'49  HP  at  150-8  revolutions  per 
minute,  8-52  BHP  was  obtained  with  a  gas  consumption  of 
18-4  cb.  ft.  per  I  HP  per  hour  and  2474  cb.  ft.  per  BHP  per 
hour.  The  test  was  made  with  Liverpool  gas,  which  evolves 
399-6  Ibs.  Centigrade  heat  units  per  cb.  ft.  at  17°  C,  or  heat 
equivalent  to  555,490  ft.  Ibs.  per  cb.  ft.  If  all  the  heat  of  the  gas 
could  be  converted  into  mechanical  work  3*564  cb.  ft.  would 
give  i  IHP  for  an  hour.  The  absolute  indicated  efficiency  of  the 

3*564  x  100 
engine  is  therefore  -      -%. =19'3  Per  cent- 

General  Remarks. — This  engine  closely  resembles  the  Clerk 
type  of  engine  in  the  arrangement  of  pump  and  motor  piston, 
but  it  is  subject  to  considerable  difficulties  in  securing  the  dis- 
charge of  the  burned  gases  without  simultaneously  losing  un- 
burned  mixture  of  gas  and  air.  The  principal  difficulty  of  all 
engines  having  open  exhaust  ports  at  the  time  of  charging  the 
cylinder  lies  in  the  proportioning  and  directing  the  flow  of  the 
entering  gas  and  air  to  displace  the  burned  gases  without  passing 
unburned  gas  away  through  this  exhaust  port.  In  the  Clerk  engine 
this  trouble  was  met  by  the  long  conical  entrance  and  considerable 
length  of  cylinder  for  the  sweep  of  the  entering  gases  ;  and  in  all 
engines  such  as  the  '  Trent '  and  the  '  Fawcett,'  where  the  power 
piston  is  discharging  gases  simultaneously  with  the  entrance  of  the 
fresh  charge,  this  trouble  is  increased,  and  it  becomes  necessary  to 
leave  large  volumes  of  exhaust  gases  in  the  cylinder  to  avoid  loss 
of  gas  at  the  exhaust  ports.  Mr.  Beechey  has  succeeded  very  well 
indeed  in  minimising  loss  from  this  cause,  as  shown  by  the  very 
fair  results  he  obtains.  He  has  the  advantage  of  greater  expan- 
sion than  the  '  Otto '  type,  although  the  disadvantage  of  greater 
proportion  of  exhaust  gas  brings  down  his  economy. 


297 


CHAPTER  II. 

OTTO    CYCLE    GAS    ENGINES. 

THE  c  Otto  cycle  engines  are  those  which  possess  at  present  a 
living  practical  interest,  and  great  advances  have  been  made  in 
them  since  1886  ;  in  particular  the  gas  consumption  has  been  much 
reduced.  The  power  of  the  engines  constructed  has  also  been 
greatly  increased.  In  1886  a  nine-horse  (nominal)  gas  engine  of 
Messrs.  Crossley's  construction  consumed  about  2 7  cb.  ft.  of  Man- 
chester gas  per  brake  horse  power  per  hour,  and  now  (1895)  a 
similar  engine  consumes  as  little  as  17  cb.  ft.  per  brake  horse 
power.  The  increase  in  power  is  also  striking  ;  engines  of  40  HP 
were  the  largest  made  in  1886,  but  now  Otto  cycle  engines  are 
built  as  large  as  400  I  HP.  It  is  interesting  to  trace  the  steps 
which  have  made  such  improvement  possible,  and  this  will  be  best 
done  by  the  study  of  the  drawings  of  Otto  cycle  engines  of  recent 
construction.  As  the  Messrs.  Crossley  are  still  the  leading  con- 
structors of  gas  engines  in  the  world,  turning  out  from  their  shops 
about  sixty  engines  every  week,  the  author  will  first  consider  one  of 
their  engines. 

Crossley  Otto  Engine. — Careful  drawings  have  been  made  of  a 
Crossley  Otto  engine  of  9  HP  (nominal)  built  in  1892,  and  now  at 
work  at  the  Clifton  Rocks  Railway,  Bristol.  The  engine  is  num- 
bered 19772.  It  has  been  thought  best  to  select  an  actual  engine 
as  an  example  in  order  to  clearly  appreciate  the  points  of  difference 
from  the  earlier  engines.  The  particular  engine  selected  was 
tested  by  the  author  for  power  and  gas  consumption.  The  engine 
shows  many  points  of  advance  over  the  1886  engines,  but  curiously 
enough,  although  it  possesses  all  the  necessary  valve  arrangements 
to  enable  high  compression  pressures  to  be  utilised,  yet  defects 
in  the  proportion  of  the  compression  space  and  piston  prevented 


298 


The  Gas  Engine 


the  use  of  high  compression,  and  the  engine  did  not  give  the  best 
economy  possible  for  the  particular  type.     Accordingly  the  gas 


1 

OH 

a 

o> 


0/3 

G 

w 

o 


consumed  per  brake  HP  hour  was  25-9  cb.  ft.     This  is  a  much 
better  result  than  would  have  been  obtained  from  a  slide  valve 


Otto  Cycle  Gas  Engines  299 

Otto  engine  such  as  illustrated  on  pages  167,  169  and  171  of  this 
work,  but  it  is  not  nearly  so  good  as  the  type  allows. 


Fig.  1 1 6  is  a  side  elevation  of  the  engine  ;  fig.  1 1 7  is  a  plan 
part  in  section;  fig.  118  an  end  elevation;  figs.  119-123  inclusive 


300 


The  Gas  Engine 


are  drawn  to  a  larger  scale;  fig.  119  is  a  side  elevation  of  the  back 
end  of  the  cylinder  looking  on  the  cam  shaft;  fig.  120  is  a  corre- 
sponding plan;  fig.  121  an  end  elevation;  fig.  122  a  vertical  longi- 
tudinal section  through  the  cylinder,  and  fig.  123  is  a  separate 
section  on  a  still  larger  scale  of  the  igniter  tube  and  funnel. 

A  comparison  of  the  illustrations  with  those  of  the  earlier  slide 
valve  engine  at  once  shows  great  mechanical  development  and 
points  of  constructive  difference.  Thus  in  the  early  engine  the 
crosshead  guide  and  the  engine  cylinder  were  two  distinct  parts 
requiring  to  be  bolted  together  in  accurate  alignment  in  order  to 

allow  the  piston  with  its  cross- 
head  slide  to  work  freely  without 
jamming  :  in  the  later  engine  a  long 
trunk  piston  is  used  which  serves 
the  double  purpose  of  piston  and 
crosshead  guide  ;  the  separate 
crosshead  slide  is,  in  fact,  dis- 
pensed with,  and  consequently  the 
cylinder  serves  as  its  own  slide 
guide,  requiring  no  adjustment  of 
separate  parts.  The  cylinder,  that 
is,  serves  both  as  cylinder  and 
slide  guide,  and  the  whole  cylinder 
is  bolted  to  the  bed  against  a 
powerful  faced  flange. 

The  bevil  wheels  of  the  early 
design  are  also  dispensed  with 
and  replaced  by  skew  or  worm  wheels,  which  besides  taking  up 
much  less  space  provide  a  much  quieter  drive  for  the  two  to  one 
shaft.  The  unsightly  distortion  of  the  bed  shown  in  fig.  5 1  neces- 
sary to  admit  the  bevil  wheels  is  quite  avoided,  as  is  clearly  seen 
at  fig.  117.  There  are  many  smaller  points  of  constructive  dif- 
ference which  the  experience  of  years  has  shown  to  be  desirable, 
but  the  great  points  of  departure  are  to  be  found  in — the  suppres- 
sion of  the  flame  slide  valve  method  of  ignition,  and  the  introduc- 
tion of  the  incandescent  tube  igniter  ;  the  diminution  of  the 
relative  volume  of  the  compression  space,  which  is  hot  carried  out 
to  its  proper  extent  in  this  individual  engine  ;  and  the  improved 


i  r 


FIG.  118.— Crossley  Otto  Engine, 
9  HP  Nominal  (end  elevation). 


Otto  Cycle  Gas  Engines  301 

proportioning  of  the  valves  and  ports  in  order  to  minimise  the 
throttling  of  the  charge  during  the  inlet  period  and  the  back 
pressure  of  the  exhaust  gases  during  discharge. 

The  engine  follows  the  same  cycle  of  operations  as  the  old 
engine;  that  is,  by  one  movement  of  the  piston  it  takes  into  the 
cylinder  a  charge  of  gas  and  air  which  is  compressed  on  the  return 
stroke  into  a  space  at  the  end  of  the  cylinder,  there  to  be  ignited 
in  order  to  give  the  explosion  and  produce  the  power  stroke  ;  the 
power  stroke  is  then  followed  by  the  exhausting  stroke,  and  the 


FIG.  119.— Crossley  Otto  Engine,  9  HP  Nominal  (side  elevation,  back  end). 

engine  is  ready  to  go  through  the  same  operations  to  prepare  for 
another  power  stroke.  In  this  engine  the  charge  of  gas  and  air  is 
admitted  by  the  inlet  valve  i,  which  is  of  the  conical  seated  lift  type ; 
the  valve  is  operated  by  the  lever  j  from  a  cam  K  on  the  valve  shaft  D. 
This  valve  shaft  is  rotated  at  half  the  speed  of  the  crank  shaft  by 
means  of  worm  wheels  or  skew  gear  E.  The  gas  supply  is  admitted 
to  the  inlet  valve  i  by  the  lift  valve  L,  which  valve  is  also  operated  by 
the  lever  and  link  N  and  cam  M,  controlled,  however,  by  the  centri- 
fugal governor  s.  The  governor  operates  to  either  admit  gas  wholly 
or  cut  it  off  completely,  so  that  the  variation  in  power  is  obtained 


302 


The  Gas  Engine 


by  varying  the  number  of  the  explosions.  The  exhaust  valve  F  is 
also  a  conical  seated  lift  valve,  and  it  is  actuated  by  the  lever  c 
and  cam  H.  The  ignition  is  produced  by  admitting  a  portion  of 
the  compressed  inflammable  charge  from  the  compression  space  to 
the  tube  R,  rendered  incandescent  by  the  Bunsen  flame.  The 


FIG.  120.— Crossley  Otto  Engine,  9  HP  Nominal  (plan,  back  end). 

passage  to  the  igniter  tube  is  controlled  by  the  valve  o,  which 
valve  is  operated  by  the  lever  Q  and  cam  P.  The  valve  o  is  double 
seated,  and  during  the  compression  period  of  the  engine  the  face 
nearest  the  compression  space  is  kept  up  against  the  seat  by  a 
powerful  spiing;  the  incandescent  tube  is  thus  kept  open  to  the 


Otto  Cycle  Gas  Engines  303 

atmosphere,  and  notwithstanding  any  leak  which  may  occur  from 
the  cylinder  the  tube  remains  empty  until  the  moment  when  it  is 
required  for  ignition.  When  the  valve  is  lifted  from  one  seat  a 
small  portion  of  the  compressed  mixture  is  discharged  through  a 
small  port  to  the  air,  and  this  clears  out  the  burned  gases, 
which  would  otherwise  render  ignition  irregular,  and  permits  pure 


FIG.  121. — Crossley  Otto  Engine,  9  HP  Nominal  (end  elevation). 

combustible  mixture  to  reach  the  incandescent  internal  surface  of 
the  tube  when  the  outer  valve  face  closes  on  its  seat.  This  device 
causes  the  ignition  of  the  explosive  mixture  at  the  proper  time. 

The  adoption  of  lift  valves  for  the  admission  and  discharge 
of  gases  to  and  from  the  engine  cylinder  simplifies  the 
practical  problem  of  admitting  and  discharging  with  the  least 
possible  throttling  or  wire  drawing.  So  long  as  slide  valves  were 


304 


The  Gas  Engine 


used  to  admit  the  charge  to  the  cylinder,  it  was  difficult  to  provide 
a  sufficiently  large  inlet  area,  as  the  area  allowed  in  a  port  bearing 
against  a  slide  surface  determined  the  pressure  necessary  to  hold 
the  slide  against  the  valve  face  to  prevent  the  escape  of  flame 


when  the  compressed  mixture  was  exploded.  In  a  six  horse- 
power engine  of  the  old  type,  for  example,  the  inlet  port  in  the 
back  cover  was  2§  inches  long  by  f  inch  wide,  equal  to  1-5  square 
inches.  Assume  the  maximum  pressure  of  the  explosion  to  be 


Otto  Cycle  Gas  Engines 


305 


150  Ibs.  per  square  inch,  then  the  slide  valve  must  be  pressed  to  its 
working  face  with  a  pressure  not  less  than  225  Ibs.  ;  as  a  matter  of 
fact  the  slide  was  pressed  up  to  its  work  with  a  pressure  of  about 
600  Ibs.  When  it  is  considered  that  the  flame  temperature 
during  the  explosion  is  about  1600°  C.  it  is  easy  to  comprehend 
the  difficulty  of  keeping  the  slide  cool  enough  to  maintain  a  good 
working  surface  even  at  comparatively  low  pressures.  Designers 
of  slide  engines  for  this  reason  were  forced  to  content  themselves 
both  with  the  minimum  of  port  area  and  with  low  compressions. 
Small  port  area  produced  naturally  considerable  resistance  to  the 
inflowing  charge,  and  low  compressions  prevented  the  attainment 
of  any  great  economy  of  gas 
consumption.  In  the  old 
engines,  the  velocity  of  flow 
of  the  air  and  gases  entering 
the  cylinder  often  exceeded 
244  feet  per  second,  so  that 
when  the  piston  reached  the 
out  end  of  its  stroke  the 
cylinder  was  not  filled  up  to 
atmospheric  pressure.  The 
evil  of  throttling  in  this  way 
was  not  confined  to  the 
active  loss  of  power  due  to 
the  resistance  to  the  charg- 
ing stroke  of  the  piston  ;  the 
greatest  loss  was  caused  by 


ir 


FIG.  123.— Crossley  Otto  Engine, 
9  HP  Nominal  (section  of  tube  igniter). 


the  considerable  reduction  in  the  weight  of  the  charge  drawn  in, 
and  the  consequent  increase  in  the  proportion  of  the  exhaust  gas 
present.  In  many  cases  it  was  found  that  the  contents  of  the 
cylinder  were  at  a  pressure  of  ij  Ib.  per  square  inch  below  atmo- 
sphere when  the  engine  terminated  its  charging  stroke,  and  this 
meant  that  the  total  volume  of  charge  admitted  was  reduced  by  20 
per  cent,  as  compared  with  the  charge  which  would  have  entered 
had  the  admission  area  been  sufficient  to  allow  the  cylinder  to  fill 
up  to  atmospheric  pressure.  The  proportion  is  greater  because  of 
the  large  volume  of  the  compression  space  which  must  be 
allowed  for  in  calculating  the  loss  due  to  deficit  of  pressure. 


The 


306  The  Gas  Engine 

slide  valve  was  undoubtedly  a  formidable  difficulty  in  these 
engines,  now  happily  overcome  by  the  substitution  of  lift  valves. 
With  lift  valves  it  is  easy  to  provide  any  desired  admission  port 
area,  as  the  pressure  of  the  explosion  holds  the  valve  to  its  seat, 
and  large  valves  may  be  used  just  as  readily  as  small  ones.  In 
the  engine  illustrated  in  figs.  116-123  the  admission  area  is  6*52 
square  inches,  with  the  valve  full  open,  and  assuming  maximum 
opening  to  remain  during  the  whole  charging  stroke  the  velocity 
of  the  entering  charge  is  only  87  feet  per  second.  This  engine 
is  therefore  better  supplied  with  combustible  mixture  than  the  old 
slide  engine. 

The  compression  pressure  in  a  slide  valve  engine  is  limited  by 
the  difficulty  of  preventing  a  slide  from  cutting  on  its  face  at  high 
compression  and  explosion  pressures,  and  this  difficulty  is  also 
overcome  by  the  use  of  lift  valves  when  combined  with  an 
incandescent  tube  igniter. 

In  the  older  engines  the  importance  of  a  free  exhaust  exit  was 
not  fully  recognised,  and  although  the  exhaust  valves  were  lift 
valves,  the  discharge  area  provided  was  insufficient.  Thus  in  the 
six-horse  slide  valve  engine  referred  to,  the  average  velocity  of  the 
exhaust  gases  past  the  exhaust  valves  was  137  feet  per  second  ; 
in  the  present  engine  it  is  only  48  feet  per  second.  The  exhaust 
gases  are  thus  better  discharged  in  the  recent  engine.  Any 
increase  in  the  volume  of  the  exhaust  products  causes  loss  of 
economy  in  a  gas  engine  ;  a  small  proportion  does  little  harm, 
but  a  large  volume  of  exhaust  heats  the  entering  charge  and  so 
raises  the  temperature  of  compression.  Premature  ignitions 
are  also  caused  by  the  compression  of  a  charge  mixed  with  hot 
exhaust.  Designers  now  endeavour  to  expel  exhaust  products 
as  completely  as  possible. 

The  engine  illustrated  has  several  bad  points,  and  it  appears 
to  the  author  to  be  one  issued  by  the  makers  while  they  were  in  a 
transition  stage,  probably  engaged  in  increasing  their  compression 
pressures.  To  get  the  best  possible  results  from  a  given  volume 
of  explosive  mixture,  it  should  be  compressed  into  a  combustion 
space,  having  the  minimum  of  port  capacity  communicating  with 
the  admission  and  exhaust  valves.  In  the  older  engines  this 
point  was  not  appreciated,  and  the  port  capacity  was  always 


Otto  Cycle  Gas  Engines  307 

excessive.  In  this  engine  the  port  capacity  back  to  the  exhaust 
and  inlet  valves  is  undoubtedly  too  great.  Ports  act  as  con- 
densers for  the  flame  of  the  explosion,  and  rapidly  cool  the  ignited 
charge  at  a  time  when  it  least  bears  cooling.  Any  narrow  spaces 
should  also  be  avoided,  and  this  engine  presents  an  example  of 
attempting  to  increase  compression,  by  means  of  the  block  v 
attached  to  the  piston,  which  should  be  carefully  avoided-  It  will 
be  noticed  that  the  block  v,  fig.  117,  projects  into  the  combustion 
space  through  the  reduced  diameter  part  x,  and  so  forms  the 
annular  space  Y  between  the  piston  .proper  and  the  reduced 
casing.  This  annulus  has  a  cooling  effect  on  the  flame  under  the 
explosion  pressure  while  the  piston  A  is  practically  stationary,  but 
it  has  a  much  more  serious  cooling  effect  whenever  the  piston 
begins  to  move  out.  The  flame  gases  then  pass  through  the  space 
between  the  piston  block  v  and  the  ring  x  into  the  annulus  Y, 
and  so  the  flame  is  dragged  through  a  cooling  or  condensing 
surface,  and  considerable  loss  is  thus  caused.  Indeed  it  may  be 
at  once  stated,  that  to  gain  the  greatest  advantage  from  high  com- 
pressions the  whole  of  the  compressed  explosive  mixture  should 
be  contained  in  one  space,  that  is  a  space  which  is  not  divided 
into  smaller  separate  spaces.  Ports  should  be  avoided  if  possible, 
and  the  flame  should  never  be  caused  to  flow  through  a  narrow 
space  into  a  wider  one,  as  is  done  in  this  engine.  The  compres- 
sion space  should  in  fact  be  as  nearly  cubical  or  spherical  as 
possible.  Notwithstanding  these  defects,  the  engine  shown  in  the 
illustration  gives  much  better  results  than  the  old  slide  valve 
engines.  For  the  purpose  of  comparison  the  author  made  prac- 
tically simultaneous  tests  on  the  engine  illustrated  and  on  an 
old  slide  valve  engine  of  six  horse  power  (nominal).  The  results 
obtained  are  given  in  the  table  on  page  310,  and  all  the  important 
valve  settings  and  numbers  are  also  given. 

Fig.  124  is  a  diagram  from  the  engine  illustrated.  It  is  a  fair 
example  of  those  taken  during  the  test. 

Fig.  125  is  the  corresponding  light  spring  diagram. 

Fig.  126  is  a  diagram  from  the  slide  valve  engine  which  has 
been  referred  to,  and  fig.  127  is  a  light  spring  diagram  also  from 
the  slide  valve  engine. 

The  scales  of  the  diagram   figs.  124  and  126  are  different,  as 


308 


The  Gas  Engine 


one  required  a  much  stronger  indicator  spring.  It  will  be  ob- 
served that  the  slide  valve  engine  only  gives  an  available  working 
pressure  of  54/8  Ibs.  per  square  inch,  while  the  lift  valve  engine 


zoo 


^•50 

< 


50 


Nominal  HP,  9;  diam.  of  cylinder,  g}" ;  length  of  stroke,  18";  revs,  per  min. 
160  ;  indicated  HP,  19*25  ;  consumpt.  per  IHP  per  hour,  21*2  cb.  ft.  ;  consumpt. 
loose,  70  cb.  ft.  per  hour  ;  brake  HP,  15*75  '•  consumpt.  per  BHP  per  hour,  25*9 
cb.  ft  ;  mean  pressure,  31*5  Ibs.  ;  max.  pressure,  203  Ibs.  ;  pressure  before  ignition, 
46  Ibs.  ;  scale  of  spring,  yf  5"  Per  lb. 

FIG.  124. — Crossley  Otto  Engine,  9  HP  Nominal  (diagram). 

gives  81-5  Ibs. ;  and  on  comparing  the  light  spring  diagrams  it  will 
be  seen  that  with  the  slide  valve  engine  the  pressure  falls  consider- 
as 


10 


0... 


Scale  of  spring,  T\"  per  Ib. ;  mean  pressure,  2*5  Ibs.  ;  charging  resistance,  0*7  IHP  ; 
total  resistance  running  loose,  3*3  IHP. 

FIG.  125. —Crossley  Otto  Engine,  9  HP  Nominal  (light  spring  diagram). 

ably  below  atmosphere  at  the  end  of  the  charging  stroke,  while 
with  the  other  engine  the  pressure  rises  nearly  to  atmosphere 
before  the  stroke  terminates. 


Otto  Cycle  Gas  Engines 


309 


Crossley  Otto  '  Scavenging*  Engine.— 'The  Crossley  Ottoengines 
now  built  differ  to  a  considerable  extent  from  the  engine  No. 


Nominal  H  P,  6  ;  diam.  of  cylinder,  8'' ;  length  of  stroke,  16"  ;  rev.  per  min.  164  ; 
indicated  HP,  9  ;  consumpt.  per  IHP  per  hour,  25*5  cb.  ft.  ;  brake  HP,  6*75  ;  con- 
sumpt.  per  BHP  per  hour,  34  cb.  ft.  ;  mean  pressure,  54*8  Ibs.  ;  max.  pressure, 
125  Ibs.  ;  pressure  before  ignition,  32  Ibs.  ;  scale  of  spring,  ^"  per  Ib. 

FIG.  126.  —Crossley  Otto  Engine,  6  HP  slide  valve  (diagram). 

19772  which  has  been  here  discussed.  Figs.  128  and  I28A  show 
the  external  appearance  of  the  present  engines.  Fig.  128  shows 
the  30  HP  nominal  engine  of  17  in.  cylinder  and  24  in.  stroke, 


25 
i  5 
<     10 

o 


-1 — r- 

Scale  of  spring,  Ty  per  Ib.  ;  mean  pressure,  3*85  ;  charging  resistance,  0*7  IHP; 
total  resistance  running  loose,  2*25  1HP. 

FIG.  127.— Crossley  Otto  Engine,  6  HP  slide  valve  (light  spring  diagram). 

intended  for  ordinary  driving  and  running  at  160  revolutions  per 
min.     Fig.  i28.\  is  the  30  HP  nominal  electric  lighting  engine  of 


3io 


The  Gas  Engine 


PRINCIPAL  PARTICULARS 

OF  A  6  NHP  CROSSLEY  OTTO  GAS  ENGINE,  BUILT  ABOUT  1881, 
AND  A  9  NHP  CROSSLEY  OTTO  GAS  ENGINE,  No.  19772,  BUILT  IN  1892. 


6  NHP  Engine,  No  4683 
6"  diam.  cylinder  x  16"  stroke 

?NHP  Engine,  No.  19772 
^"diam.  cylinder  x  i8"stroke 

Volume  swept  by  piston 

804  cub.  ins. 

i275'8  cub.  ins. 

Volume  of  compression  space. 

516  cub.  ins. 

510  cub.  ins. 

Vol.  swept  by  piston 

804        i 

j275-8_^_ 

Vol.  of  comp.  space       * 

51  6  =  0^64 

510       o_4 

Compression  pressure     . 

f  31  Ibs.  per  sq.  in.  above 
(    atmos. 

^8   Ibs.    per  sq.    in.    above 
atmos. 

Explosion  pressure  . 

(  125  Ibs.  per  sq.  in.  above 
(    atmos. 

200  Ibs.   per  sq.  in.  above 
atmos. 

Mean  available  pressure 

57  Ibs.  per  sq.  in. 

Si's  Ibs.  per  sq.  in. 

Revelations  per  minute  . 

164 

160 

Indicated  horse  power    . 

9'0 

i9'25 

Brake  horse  power  . 

6-75 

"5*75 

Gas  consumption  per  hour 
(including  ignition) 

236  cub.  ft. 

4-  8  cub.  ft. 

Gas  per  I  HP  per  hour    . 

25  '5  cub.  ft. 

21*2  cub.  ft. 

Gas  per  BMP  per  hour  . 

34  cub.  ft. 

25*9  cub.  ft. 

Mechanical  efficiency      . 

75  per  cent. 

8  1  per  cent. 

Area  of  charge  inlet  port 

(Slide  valve)  1*5  sq.  in.     -j 

(In'et  valve   2$"  diam.  x  §" 
lift)  6*52  sq.  ins. 

i                                               \ 

Opens  dead  on  in  centre,  is 

Is  1"  open  when  piston  is         l.eld   open   on   out  centre, 

Inlet  port  setting    . 

on  in  centre,  and  £"  open  !       and  closes  when  the  piston 
when   piston   is    on  out,       returns   ii".in.     At   i"  in  ' 

centre 

movement    of   piston    the 

Exhaust  valve 

/ 
\(z\"  diam.  xjj"  lift)  2*65 

valve  is  -f.."  open 
.(3"    diam.  x  ij"    lift)    ii'78 

i    sq.  in.  area 

sq.  in.  area 

|  Opens  while  piston  is  i" 

|    in  from  out  end  of  stroke. 

Opens  while   piston   is   2}"  , 

Exhaust  valve  setting    . 

•j    Closes  when  piston   has  - 

from   out    end    of   stroke. 

I    crossed    in    centre    and  1 

Closes  exactly  on  in  centre. 

I   moved  out  J"                    ; 

j'                                            1 

(Lift    valve    tube     igniter) 

Ignition  lead  .... 

j  Ignition  port  in  slide  is  an 
-|    i"  open  when  crank  is  on  r 

valve  TV'  diam.  x  Ty  lift, 
opens  i\"  before  compres- 
sion is  complete,  but  only 

1    ln  centre                             l 

full   open   \"  before  com- 

Charge velocity 
Exhaust  velocity     . 
Piston  speed    .... 
Power  absorbed  charging  and 
exhausting  .... 

I                                              J 

244  ft.  per  sec. 
137  f>.  per  sec. 
437  ft.  per  min. 

07  IHP 

pression  is  complete 
87  ft.  per  sen. 
48  ft.  per  sec. 
4  Co  ft.  per  min. 

0-7  IHP 

Gas  inlet  valve        , 

|"  diam.  x  §"  lift 

i"  diam.  x§"  lift 

/                                          '    \ 

When  piston  has  gone  -z\" 

Gas  inlet  valve  setting    .        » 

When  piston  has  made  i\" 
4    forward      stroke     valve  !- 

forward  stroke  valve  opens, 
and  does  not  close  till  out 
centre  has  been  crossed  and 

opens 

Eiston  returns  i\".     Valve 

i  f\"  open  when  piston  is 

V                                              / 

full  out 

! 

17  in.  diam.  cylinder  and  21  in.  stroke,  which  runs  at  230  revolu- 
tions per  min.,  and  with  coal  gas  will  indicate  a  maximum  power 
of  117  horse.  The  engines  now  supplied  are  of  the  'scavenging' 


312 


The  Gas  Engine 


type.  The  general  external  appearance  is  similar  to  that  illus- 
trated, but  an  important  modification  is  made  in  the  operations 
performed  by  the  engine.  In  addition  to  the  cycle  of  operations 


described,  the  engine  is  so  arranged  that  the  exhaust  gases 
formerly  remaining  in  the  combustion  space  are  swept  out  and 
the  combustion  space  filled  with  air.  The  combustible  charge  in 
this  engine  is  therefore  a  pure  mixture  of  gas  and  air  without  any 


Otto  Cycle  Gas  Engines 


3'3 


exhaust  gases.  To  accomplish  this  clearing  out  of  the  burned 
gases  and  their  replacement  by  air,  advantage  is  taken  ot  the 
oscillations  or  waves  of  pressure  set  up  in  the  exhaust  pipe  by 
the  discharge  of  the  exhaust  gases.  It  has  long  been  known  that 
in  a  gas  engine  exhaust  pipe  the  pressure  of  discharge  is  suc- 
ceeded by  a  partial  vacuum,  and  this  vacuum  again  succeeded 


FIG 


FIG.  129. — Crossley  Otto  Scavenging  Engine  (vertical  section  of  cylinder). 
FIG.  130. — Do.  (sectional  plan  of  cylinder). 

by  pressure,  in  fact  that  under  certain  circumstances  an  oscilla- 
tion of  pressure  is  set  up  in  the  exhaust  pipe,  giving  a  fall  of 
pressure  at  certain  periods  after  the  exhaust  valve  is  opened. 
Messrs.  Crossley  &  Atkinson  take  advantage  of  this  fact,  and 
so  control  the  pressure  wave  and  the  following  vacuum  that  after 
the  exhaust  gases  have  been  liberated  from  the  cylinder  of  the 


The  Gas  Engine 

engine  the  high-pressure  discharge  is  "succeeded  by  a  vacuum, 
the  period  of  the  vacuum  coinciding  with  the  approach  of 
the  piston  to  the  end  of  its  exhaust  stroke.  By  then  keeping 
open  the  exhaust  valve  and  opening  the  charge  or  an  inlet  valve 
while  the  exhaust  valve  is  open,  a  charge  of  pure  air  is  drawn 


FIG.  iii. 


FIG.  131.  —  Crossley  Otto  Scavenging  Engine  (end  elevation). 
FIG.  132.— Do.  (transverse  section). 

through  the  combustion  space  to  sweep  out  the  burned  gases  from 
the  compression  space.  When  the  charging  stroke  is  complete 
the  whole  cylinder  is  thus  filled  with  a  pure  mixture  of  gas  and 
air  without  the  deleterious  burned  gases.  To  accomplish  this 
sweeping  out  in  a  satisfactory  manner  it  is  necessary  to  shape  the 
cylinder  so  as  to  favour  the  free  flow  of  the  entering  air. 


Otto  Cycle  Gas  Engines 


315 


Figs.  129,  130,  131,  132  are,  respectively,  vertical  section;  sec- 
tional plan  ;  end  elevation  ;  and  transverse  section  illustrating  the 
arrangement  of  a  4  HP  nominal  engine  tested  by  the  author  at 
Messrs.  Crossley's  works  in  Manchester. 

I  Fig.  133  illustrates  in  a  diagrammatic  way  the  settings  of  the 
valves  in  that  engine. 

;  The  desired  delay  in  the  production  of  the  vacuum  is  brought 
about  by  attaching  an  exhaust  pipe  c  of  about  65  ft.  long.  Quiet- 
ing chambers  may  be  placed  at  the  end  of  that  length  of  pipe 
without  affecting  the  result,  but  no  large  expansion  or  chamber 
should  be  put  nearer  to  the  engine  cylinder.  The  energy  of  dis- 
charge of  the  exhaust  sets  the  long  column  of  gases  filling  the 
pipe  in  oscillating  motion,  and  enables  a  considerable  reduction  of 
pressure  to  be  produced  just  as  the  piston  is  completing  its  ex- 


FIG.  133. — Crossley  Otto  Scavenging  Engine  (valve  settings). 

hausting  stroke.  Fig.  134  is  a  light  spring  diagram  taken  from  the 
engine  during  the  author's  test,  and  it  plainly  shows  the  effect  of 
the  vacuum  so  produced  in  the  exhaust  pipe.  It  will  be  noted 
that  at  the  termination  of  the  exhausting  stroke  the  pressure  in 
the  cylinder  has  fallen  to  2  Ibs.  per  square  inch  below  atmosphere, 
a  reduction  of  pressure  amply  sufficient  to  cause  a  flow  of  air  from 
the  atmosphere  sweeping  through  the  cylinder. 

On  figs.  130  to  132  the  arrows  show  the  direction  of  the  air 
current  passing  in  by  the  inlet  valve  A  through  the  specially  shaped 
c)  Under  and  out  at  the  exhaust  valve  B. 

In  fig.  133  the  air  inlet  valve  is  opened  while  the  crank  is  in 
the  position  D,  and  the  exhaust  valve  is  held  open  till  the  crank 
reaches  the  position  B.  The  exhaust  valve  opens  again  at  A,  and. 
it  is  held  open  to  B  position  instead  of  as  usual  to  c  position.  The 


316 


The  Gas  Engine 


inlet  valve  is  thus  held  open  during  the  existence  of  a  partial  vacuum 
in  the  exhaust  pipe,  and  so  a  *  scavenging  '  charge  of  air  is  drawn 


Scale  of  spring,  T\"  per  Ib.  ;  charging  and  scavenging  diagram  ; 
charging  diagram  of  4  NHP  Crossley  Otto  Engine. 

FIG.  134.  — Crossley  Otto  Scavenging  Engine  (light  spring  diagram), 
through  the  combustion  space  and  the  products  replaced  by  pure 
Fig.  135  is  a  diagram  taken  by  the  author  during  his  test  of  the 


air. 


s 


Nominal  HP,  4  ;  diam.  of  cylinder,  7" ;  length  of  stroke,  15" ;  rev.  per  min.  200  ; 
indicated  HP,  14  ;  consumpt.  per  IHP  per  hour,  14-5  cb.  ft.  ;  brake  HP,  11*97; 
consum^t.  per  BHP  per  hour,  17*0  cb.  ft.  ;  mean  pressure,  loo'g  Ibs.  ;  max. 
pressure,  274  Ibs.  ;  pressure  before  ignition,  87  Ibs.  ;  spring,  TSO"- 

FIG.  135.— Crossley  Otto  Scavenging  Engine  (power  diagram). 

scavenging  engine  at  Messrs.  Crossley's  works,  Openshaw.  The 
leading  particulars  are  marked  upon  the  diagram,  from  which  it 
will  be  observed  that  the  engine  gave  results  which  were  most 


Otto  Cycle  Gas  Engines 


317 


remarkable  botk  from  the  points  of  power  and  economy.  The 
engine,  although  only  7  in.  diam.  cylinder  and  15  in.  stroke,  gave 
practically  i2-brake  horse  power  on  a  gas  consumption  of  17  CD.  ft. 
per  brake  horse  power  hour,  a  surprisingly  good  result  for  so  small 
an  engine.  Openshaw  gas  is  20  candle  power,  and  has  a  heat 
value  of  53,000  ft.  Ibs.  per  cb.  ft. 

Diagrams  and  Gas  Consumption. — The  diagrams  given  at  figs. 
124,  125,  126,  127,  134  and  135  illustrate  very  fairly  the  progress 
made  in  the  Crossley  Otto  engine  from  the  old  slide  valve  engine 
to  the  present  lift  valve  scavenging  engine,  and  it  is  interesting  to 
compare  the  consumption  of  these  three  engines.  They  are  as 
follows  : 


Gas 
per  I  HP  hour 

Gis 
per  BHP  hour 

Compression 
pressure  per  sq. 
in.  above  atmos. 

Slide  valve  engine 
Lift  valve  engine,  No.  19772 
Lift  valve  scavenging  engine 

25-5  cb.  ft. 
21  '2  Cb.   ft. 

14-5  cb.  ft. 

34  Cb.  ft 
25-9  cb.  ft. 
17  cb.  ft. 

30  Ibs. 
46  Ibs. 
87  -5  Ibs. 

The  advance  made  by  the  Messrs.  Crossley  is  quite  unmis- 
takable ;  the  brake  consumption  is  now  just  about  half  of  the 
consumption  in  a  Crossley  Otto  engine  built  in  1881.  No  doubt 
many  of  their  slide  valve  engines  were  more  economical  than  the 
one  tested  by  the  author,  and  the  gas  consumption  of  engine 
No.  19772  does  not  represent  the  most  favourable  result  attained 
by  the  Messrs.  Crossley  before  the  advent  of  the  scavenging  engine. 
Thus  the  Crossley  engine  tested  at  the  Society  of  Arts  trials  at  the 
end  of  1888  had  a  cylinder  of  9-5  ins.  diameter  and  a  stroke  of 
1 8  ins.  The  gas  consumed  per  indicated  horse  power  per  hour 
was  20'55  cb.  ft.  and  per  brake  horse  power  23*87  cb.  ft.  The 
compression  pressure  was  6r6  Ibs.  per  sq.  in.  above  atmosphere. 
The  indicated  power  was  17-12  horse,  brake  power  1474  horse, 
and  the  speed  of  the  engine  160  revs,  per  minute.  The  mean 
effective  pressure  was  67-9  Ibs.  per  sq.  in.  and  the  initial  pressure 
of  the  explosion  197  Ibs.  per  sq.  in.  above  atmosphere. 

The  author's  test  of  the  4  HP  Crossley  Otto  scavenging 
engine  was  made  in  August  1894,  so  that,  taking  the  Society  of 
Arts  Crossley  engine  as  the  most  economical  up  to  that  date/from 


-318  The  Gas  Engine 

1888  to  1894  the  Messrs.  Crossley  succeeded  in  reducing  the  gas 
consumption  per  brake  horse  power  from  24  to  17  cb.  ft. 

It  is  to  be  remembered  that  this  figure  of  17  cb.  ft.  per 
brake  HP  was  obtained  with  a  small  engine.  Mr.  Atkinson,  of 
Messrs.  Crossley,  has  given  the  author  results  of  a  test  made  with 
an  engine  of  n|  in.  diam.  cylinder  and  21  in.  stroke  also  at  Man- 
chester. The  power  indicated  was  46*8  horse,  and  the  gas  con- 
sumption was  only  i3'55  cb.  ft.  per  IHP  hour.  The  consumption 
of  17  cb.  ft.  per  brake  HP  per  hour  is  the  lowest  of  which  the 
author  has  experience  with  an  engine  so  small.  It  will  be  observed 
that  increasing  economy  in  the  Crossley  Otto  engine  has  always 
been  accompanied  by  an  increase  of  compression;  thus  a  compres- 
sion of  30  Ibs.  in  the  slide  valve  engine  of  1881  has  been  displaced 
in  1894  by  a  compression  of  87-5  Ibs. 

Compression  has  evidently  some  part  in  securing  the  advan- 
tages of  the  present  engine.  Mr.  Atkinson,  in  a  paper  read  before 
the  Manchester  Association  of  Engineers,  attributes  the  whole  cf 
the  economy  of  the  recent  engine  to  the  discharge  of  the  burned 
gases  and  their  replacement  by  pure  air.  In  this  the  author  does 
not  agree  with  him  ;  he  will,  however,  reserve  the  discussion  of  the 
matter  to  a  general  chapter  upon  gas  engine  economy,  and  he  will 
now  proceed  to  give  a  short  account  of  the  Otto  engines  of  other 
makers. 

The  Stockport  Otto  Engine.— Messrs.  J.  E.  H.  Andrew  &  Co. 
of  Reddish  now  build  a  well-designed  and  carefully  made  Otto 
engine  which  they  call 'the  '  Stockport  Otto.'  Figs.  136,  137  and 
138  illustrate  its  principal  details.  Fig.  136  is  a  side  elevation  of 
the  cylinder  and  back  part  of  the  engine  frame  showing  the  back 
cover  in  longitudinal  section  through  the  admission  valves.  Fig.  137 
is  an  end  elevation  looking  on  the  back  cover,  partly  in  section  to 
show  the  igniting  valve,  the  charging  valve,  and  the  exhaust 
valve. 

Fig.  138  is  a  section  on  a  larger  scale  of  the  incandescent  tube 
and  the  timing  and  starter  valve. 

In  fig.  136  the  gas  and  air  admission  valve  is  shown  nearest  to  the 
combustion  space,  the  air  to  supply  it  being  drawn  along  a  passage 
cast  outside  the  cylinder  water  jacket,  from  the  bed  of  the  engine, 
which  serves  as  an  air  suction  silencer.  The  gas  supply  valve  is  shown 


Otto  Cycle  Gas  Engines  319 

outside  the  charge  admission  valve  ;  it  is  pressed  down  to  its  seat 
by  a  spring  above  it,  and  when  it  is  lifted  the  gas  from  the  gas  pipe 


FIG.  136.—  Stock  port  Otto  Engine  (side  elevation). 


FIG.  137. — Stockport  Otto  Engine  (end  elevation). 

passes  directly  into  the  chamber  under  the  charging  valve  and 
mixes  with  the  air  entering  the  cylinder.     The  gas  valve  is  operated 


320 


The  Gas  Engine 


by  a  lever  similar  to  those  shown  in  fig.  137,  but  the  centrifugal 
governor  shown  in  fig.  136  controls  the  lever  by  means  of  an  inter- 
posing lever  shown  as  connected  to  the  governor  sleeve.  A 
short  straight  port  communicates  with  the  interior  of  the  cylinder 
from  above  the  charging  valve.  In  fig.  137  the  charging  valve  is 
again  seen  in  section  in  the  middle  of  the  cylinder  ;  the  exhaust 
valve  is  also  shown  in  section  at  the  left-hand  side  of  the  drawing  ; 
both  valves  are  brought  to  their  seats  by  springs,  and  are  operated 


FIG.  138. — Stockport  Otto  Engine  (section  incandescent  tube  and  starter). 

by  levers  from  the  side  shaft.  In  fig.  137  is  also  shown  a  section 
of  the  igniter  tube  and  its  timing  valve.  The  timing  valve  opens 
into  the  port  above  the  admission  valve,  and  it  is  controlled  by  a 
lever  and  cam  shown.  From  fig.  137  it  will  be  seen  that  the  exhaust 
valve  is  also  connected  to  the  cylinder  by  a  short  straight  port. 
The  section  of  igniter  tube  and  starting  valve,  fig.  138,  shows  an 
incandescent  metal  igniter  tube  G,  heated  in  the  usual  manner, 
but  having  a  small  internal  tube  passing  into  it  from  the  space 


Otto  Cycle  Gas  Engines 


321 


controlled  by  the  timing  valve  F.     The  valve  A  is  used  for  starting, 
and  will  be  described  later  on.-    The  lever  D  opens  the  timing 


d 

Nominal  HP,  Q  ;  diam.  of  cylinder,  c|"  ;  length  of  stroke,  17"  ;  rev.  per  min.  184; 
consumpt.  per  I  HP  per  hour,  19  cb.  ft.  ;  brake  HP,  20*8  ;  consumpt,,  per  BHP  per 
hour,  22*3  cb.  ft.  ;  consumpt.  loose,  63*6  cb.  ft.  ;  mean  pressure,  gi'8  Ibs.  ;  max. 
pressure,  230  Ibs.  ;  pressure  before  ignition,  60  Ibs.  ;  scale  of  spring,  TJ1,o"  per  Ib. 

FlG.  139. — Stockport  Otto  Engine  (power  diagram,  60  Ibs.  compression). 


Nominal  HP,  9  ;  diam.  of  cylinder,  9!";  length  of  stroke,  17"  ;  rev.  per  min.  182  ; 
consumpt.  per  IHP  per  hour,  17*6  cb.  ft.  ;  brake  HP,  24*4  ;  consumpt.  per  BHP 
per  hour,  20*75  ;  consumpt.  loose,  72  cb.  ft.  ;  mean  pressure,  ioi'i  Ibs.  ;  max. 
pressure,  270  Ibs.  ;  pressure  before  ignition,  yo  Ibs.  ;  scale  of  spring,  Y^Q  '  Per  lb. 

FIG.  140.— Stockport  Otto  Engine  (power  diagram,  90  Ibs.  compression). 

valve  F  at  the  proper  moment  and  admits  compressed  inflammable 
mixture  from  the  port  above  the  admission  valve  of  the  engine  to 

Y 


322 


The  Gas  Engine 


the  tube  G  by  way  of  the  internal  tube.  The  mixture  then  ignites, 
and  the  explosion  is  communicated  to  the  cylinder.  The  chamber 
above  the  valve  A  serves  to  cause  a  sufficient  rush  through  the 
tube  G  to  make  certain  that  explosive  mixture  reaches  the  incan- 
descent surface  of  the  tube  ;  the  valve  F  is  held  open  long  enough 
to  allow  the  whole  of  the  contents  of  the  spaces  and  igniter  to 
discharge  into  the  exhaust  valve  so  as  to  be  ready  for  another 
explosion. 

Diagrams  and  Gas  Consumption. — Mr.  A.  R.  Bellamy  of 
Messrs.  Andrew  &  Co.  has  been  good  enough  to  send  the  author 
the  diagrams,  figs.  139  and  140,  which  have  been  taken  by  him 
from  a  Stockport  Otto  engine  of  the  construction  described.  The 
engine  had  a  cylinder  of  9!  in.  diameter  and  a  stroke  of  17  in. 
The  particulars  of  each  test  have  been  marked  under  the  diagram. 


Scale  of  spring,  Ty  per  Ib.  ;  charging  diagram  from   Engine  No.  6242  at  60  Ibs. 
compression. 

FIG.  141. — Stockport  Otto  Engine  (light  spring  diagram). 

The  diagrams  are  especially  interesting,  as  they  are  taken  from 
the  same  engine,  but  with  a  smaller  compression  space  in  the  one 
case  than  in  the  other.  In  the  first  diagram  the  compression  space 
is  proportioned  to  give  a  compression  pressure  of  60  Ibs.  pet  square 
inch,  while  in  the  second  the  compression  is  90  Ibs.  per  square 
inch  above  atmosphere.  The  difference  in  economy  is  marked,  as 
with  the  lower  compression  the  engine  consumed  19  cb.  ft.  per 
IHP  hour,  and  with  the  higher  compression  only  17-6  cb.  ft.  per 
I  HP  hour.  Fig.  141  is  a  light  spring  diagram  from  the  same 
engine. 

Stockport  Otto  400  HP  Engine. — Messrs.  Andrew  &  Co.  have 
built  perhaps  the  largest  gas  engine  in  the  world,  and  they  have 
kindly  supplied  the  author  with  drawings  from  which  the  illustra- 


Otto  Cycle  Gas  Engines  .323 

tions,  figs.  142,  146,  have  been  prepared.  The  principal  dimen- 
sions and  a  list  of  the  parts  are  marked  upon  the  figures.  The 
arrangement  of  the  engine  is  novel  and  interesting  ;  two  cylinders 


i:  «ii 


S    SI*! 

<  felal 
^  ^ 


Y2 


324 


The  Gas  Engine 


are  mounted,  tandem  fashion,  on  a  bed  plate.  To  avoid  passing 
a  piston  rod  through  a  combustion  space  the  pistons  are  connected 
by  a  system  of  piston  rods,  crossheads  and  side  rods  ;  both  pistons 
thus  connect  to  one  crank  shaft  by  a  common  connecting  rod. 
Each  cylinder  operates  on  the  Otto  cycle,  but  the  valves  are  timed 
to  make  the  explosions  alternate,  and  so  an  impulse  is  obtained  for 
every  revolution  of  the  fly-wheel. 

The  engine  is  applied  to  actuate  a  mill  at  Godalming,  and  it  is 





FIG.  144.— Stockport  Otto  Engine,  400  IHP 
(end  elevation  with  valve  in  section). 

supplied  with  gas  generated  by  a  Dowson  plant.  The  maximum 
indicated  power  is  stated  to  be  400  horse.  The  author  has  not  as 
yet  obtained  indicator  diagrams  from  this  engine. 

Barker's  Otto  Engine.— In  the  examples  which  have  been  given 
of  the  Crossley  and  Stockport  Otto  engines  it  will  be  observed  that 
both  charging  and  exhausting  valves  communicate  with  the  interior 
of  the  cylinder  by  ports  of  considerable  dimensions.  The  ports  in 
the  Stockport  engines  are  smaller  than  those  in  the  Crossley ; 


Otto  Cycle  Gas  Engines 


325 


other  conditions  being  similar,  an  engine  where  the  whole  of  the 
mixture  is  contained  in  one  large  space,  without  small  subsidiary 
spaces,  is  less  liable  to  loss  of  heat  at  the  maximum  temperature 
of  the  explosion.  It  follows  from  this  that  if  ports  and  passages 
can  be  avoided,  then  greater  economy  will  be  obtained.  It  is  very 
convenient  from  a  constructive  point  of  view  to  build  gas  engines 
with  ports,  because  it  allows  the  charging  and  admission  valves 
to  be  contained  in  separate  casings,  which  can  be  bolted  on  the 
cylinder  facings.  Such  casings  also  allow  of  the  easy  removal 
of  the  valves  for  cleaning,  by  merely  unscrewing  a  light  cover. 


FIG.  145. — Stockport  Otto  Engine,  FIG.  146.— Stockport  Otto  Engine, 
400  IHF  (longitudinal  section  through  400  IHP  (longitudinal  section  through 
exhaust  valve).  gas  and  air  valves). 

Notwithstanding  the  great  convenience  of  passages,  it  is  important 
to  dispense  with  them. 

Messrs.  T.  B.  Barker  &  Co.  of  Birmingham  have  kept  this 
point  well  in  view  in  designing  their  Otto  engine,  which  is  illustrated 
at  figs.  147-149.  Fig.  147  is  a  side  elevation  of  the  engine  with 
part  of  the  cylinder  in  section  to  show  the  valve  arrangements. 
Fig.  148  is  a  plan  and  fig.  149  is  an  end  elevation.  Here  port 
surface  has  been  practically  abolished,  as  the  valves  are  placed  so 
as  to  open  directly  into  the  cylinder.  The  exhaust  valve  i  and 
the  charging  valve  2  are  carried  in  separate  turned  sleeves,  which 
fit  into  bored  recesses  terminating  at  their  inner  ends  in  conical 


326 


The  Gas  Engine 


valve  seats.     The  sleeves  are  held  up  to  their  respective  conical 
seats  by  a  bridge  piece  3  screwed  on  by  the  single  nut  4.     The 


ends  of  the  bridge  piece  bear  upon  the  ends  of  the  sleeves,  and  on 
screwing  up  the  nut  4  both  sleeves  are  firmly  pressed  home.  The 
valves  are  pulled  to  their  seats  by  the  spring  5  which  also  acts  by 


Otto  Cycle  Gas  Engines 


327 


a  bridge  or  stirrup.  The  valves  are  opened  by  levers  6,  one  of 
which,  the  admission  valve,  is  here  seen  in  the  end  elevation,  fig.  149. 
The  levers  are  operated  by  cams  on  the  usual  two  to  one  shaft. 


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328 


The  Gas  Engine 


By  this  arrangement  the  upper  surface  of  the  exhaust  valve  i 
forms  part  of  the  interior  surface  of  the  cylinder,  and  so  far  as  the 
exhaust  valve  is  concerned  the  prejudicial  port  surface  is  abolished. 
The  charging  valve  2  also  opens  directly  into  the  cylinder,  but 
here  it  has  been  found  advisable  to  allow  the  charge  to  enter  the 
cylinder  by  way  of  a  recess  or  cavity  7  ;  this  recess,  however,  is  very 
open,  and  does  not  appreciably  increase  the  cooling  surface.  It 
has  been  found  desirable  to  have  a  cavity  7  in  order  to  make  cer- 
tain of  pure  inflammable  mixture  for  the  igniting  tube.  This  is 
the  more  necessary  as  the  igniting  tube  operates  without  requiring 
a  timing  valve. 

The  gas  valve  is  shown 
at  8,  fig.  149,  and  it  is 
operated  by  the  lever  9, 
the  governor  TO  controlling 
the  gas  supply  in  the  usual 
manner.  The  ignition  tube 
1 1  remains  at  all  times  open 
to  the  engine  cylinder,  and 
the  time  of  ignition  is  ad- 
justed by  the  position  of 
the  incandescent  part  of 
the  tube.  To  vary  this 
position  the  Bunsen  burner 
is  moved  upwards  or 
downwards  as  required, 
ignition  is  obtained  in  this 


FIG.  149. — Barker's  Otto  Engine 
(end  elevation). 


A   very   accurate    adjustment   of 
way. 

The  air  supply  is  admitted  to  the  annulus  1 2,  and  it  passes 
through  apertures  in  the  sleeve  carrying  the  admission  valve. 
The  exhaust  gases  are  discharged  by  way  of  the  pipe  13. 

The  engine  illustrated  is  of  12  HP  nominal,  and  it  gives 
excellent  results,  as  may  be  seen  from  the  accompanying  dia- 
grams, figs.  150  and  151.  Fig.  150  is  a  diagram  taken  with 
the  engine  fully  loaded,  and  fig.  151  with  the  engine  running 
light  without  load.  The  timing  of  the  ignition  when  running 
without  load  is  as  perfect  as  v/hen  full  load  is  carried.  These 
tw.o  diagrams  prove  that  the  open  tube  igniter  without  timing 


Otto  Cycle  Gas  Engines 


329 


valve  is  quite  capable  of  producing  accurately  timed  explosions 
under  widely  varying  conditions  of  temperature  and  composition 
of  mixture. 

Diagrams  and  Gas  Consumption. — An  engine  of  the  kind 
illustrated  was  tested  at  the  Saltley  Gas  Works  of  the  Birmingham 
Corporation  at  the  beginning  of  1894  by  Mr.  J.  W.  Morrison. 
Fig.  152  is  one  of  the  diagrams  then  obtained  with  the  principal 
results  of  the  test  marked  under  it.  From  this  it  appears  that 
the  engine  consumed  as  an  average  of  four  experiments  21-3 

300 


(YIP    76  LBS 


Nominal  HP,  12  ;  d'am.  of  cylinder,  TO''  ;  length  of  stroke,  18'  ;  revs  per  min  180 ; 
indicated  HP,  24  4  ,  consumpt  per  IHP  per  hour,  18  cb.  ft.  ;  consumpt.  per  BHP 
per  hour,  21 '5  cb.  ft.  ;  mean  pressure,  76  Ibs.  ;  max.  pressure,  250  Ibs.  ;  pressure 
before  ignition,  51  Ibs.  -  scale  of  spring  i\^"  per  Ib 

Fig.  150. — Full  Load  Diagram.      12  NHP  Barker  Otto  Engine. 

cb.  ft.  of  gas  per  brake  HP  per  hour,  or  17^2  cb.  ft.  per  IHP 
hour  This  is  an  admirable  result  with  Birmingham  gas.  As  the 
compression  was  only  50  Ibs.,  it  is  evident  that  much  of  the 
efficiency  of  the  engine  was  due  to  the  very  good  arrangement  of 
the  combustion  space  and  valves.  This  engine  was  designed 
for  Messrs.  Barker  by  Mr.  F,  W  Lanchester,  In  the  author's 
opinion  Mr  Lanchester  is  to  be  congratulated  on  the  excellence 
of  the  results.  At  the  time  the  test  was  made  the  author  believes 
the  consumption  to  be  the  lowest  then  recorded. 

Tangyes?  Otto  Engine.—  The  Otto  gas  engine  constructed  by 


330 


The  Gas  Engine 


Messrs.  Tangye  does  not  appear  to  have  any  features  calling  for 
special  mention.     In  the  smaller   engines   Pinkney's   ingenious 


250 
200 
ISO 
100 
50 


Scale  of  spring,  T^"  per  Ib. ;  rev.  per  min.  194 ;  running  light. 
FIG.  151.— No  Load  Diagram.     12  NHP  Barker  Otto  Engine. 

momentum   governor,  described  on  page  235  of  this   work,    is 
adapted  to  the  Otto  cycle,  but  in  the  larger  engines  the  centrifugal 


1 80 


60 


MP    68  5     LBS. 


Maximum  brake  HP,  30  ;  diam.  of  cylinder,  12"  ;  length  of  stroke,  20"  ;  indicated 
HP,  36^6  ;  consumpt.  per  IHP  per  hour,  17*7  cb.  ft.  ;  brake  HP,  29*8  ;  consumpt. 
per  BHP  per  hour,  21*8  cb.  ft.  ;  mean  pressure,  68*5  Ibs.  ;  max.  pressure,  180  Ibs.  ; 
pressure  before  ignition,  50  Ibs.  ;  rev.  per  min.  207 '25  ;  scale  of  spring,  T^5"  per  Ib. 

FIG.  152.— Saltley  Diagram.     Barker  Otto  Engine. 

governor  is  used.  The  combustion  chamber  also  is  somewhat 
conical  instead  of  being  cylindrical.  Indeed,  Messrs.  Tangye 
appear  to  claim  special  advantages  in  silencing  the  explosion  by 


Otto  Cycle  Gas  Engines 


331 


332  The  Gas  Engine 

means  of  this  conical  shape ;  no  doubt  a  conical  chamber  does 
possess  certain  advantages,  and  these  advantages  were  fully 
appreciated  by  the  author  as  early  as  the  year  1880,  as  may  be 
seen  by  examining  the  section  of  his  engine  on  page  187  of  this 
work. 

Messrs.  Tangye's  engine  is  well  made,  and  the  design  is 
characteristic.  Fig.  153  illustrates  the  general  appearance  of  the 
engine,  and  fig.  154  is  a  diagram  which  Messrs.  Tangye  were 
good  enough  to  send  the  author,  giving  the  results  claimed  by 
them  for  a  large  gas  engine. 


Nominal  HP,  35  ;  diam.  of  cylinder,  18"  ;  length  of  stroke,  24"  ;  rev.  per  min.  160  ; 
consumpt.  per  IHP  per  hour,  i4'7  cb.  ft.  ;  3  explosions  per  cb.  ft.  of  town  gas  ; 
mean  pressure,  89  Ibs.  ;  max.  pressure,  220  Ibs.  ;  initial  pressure  before  ignition, 
73  Ibs.  ;  scale  of  spring,  ^". 

FIG.  154.— Diagram  from  35  NHP  Tangyes'  Otto  Engine. 

Burfs  Compound  Otto  Engine. — Many  attempts  have  been 
made  to  utilise  the  compound  principle  in  the  gas  engine  in  order 
to  expand  the  compressed  charge  to  a  greater  volume  than  that 
existing  before  compression.  Otto,  Crossley,  Atkinson,  Clerk 
and  many  others  have  experimented  in  this  direction,  but  so  far 
without  success.  The  engine  known  as  Burt's  Acme  Compound 
Engine  is  in  reality  an  expansion  engine  and  not  a  compound,  as 
in  it  the  full  initial  pressure  is  applied. to  both  cylinders.  That  is, 
both  pistons  .get  the  maximum  pressure  of  the  explosion ;  the 


Otto  Cycle  Gas  Engines  333 

pistons  between  them,  however,  expand  the  compressed  gases  to  a 
greater  volume  than  their  volume  before  compression,  and  so  the 
engine  is  well  worthy  of  study  by  engineers  interested  in  some 
difficulties  of  compound  gas  engines. 

Professor  W.  T.  Rowden,  writing  on  a  report  on  the  engine 
giving  the  results  of  a  test  made  in  Glasgow,  says  :  '  The  chief 
novelty  in  the  engine  is  the  method  of  obtaining  expansion  of  the 
fired  charge  beyond  the  volume  occupied  by  the  mixed  gases  at 
the  end  of  the  intake  portion  of  the  cycle. 

*  From  the  Otto  and  Clerk  engines,  and  from  others  which  are 
more  or  less  copies  of  these  two  types,  the  products  of  combustion 
begin  to  escape  whilst  still  at  a  pressure  of  from  30  to  40  Ibs. 
above  atmosphere.  The  "  Acme "  engine  secures  the  desired 
expansion  in  a  simple  manner,  and  the  exhaust  is  almost  noiseless. 
Moreover,  the  temperature  of  the  exhausted  gases  is  so  reduced 
by  the  cooling  effect  of  the  expansion  as  to  remove  all  danger  of 
fire  from  a  heated  exhaust  pipe.  Referring  to  the  engraving 
of  a  2  HP  (nominal)  engine  [see  fig.  155],  it  will  be  seen  that 
two  cylinders,  pistons  and  shafts  are  used,  the  two  shafts  being 
connected  by  toothed  wheels,  which  are  geared  in  the  ratio  of 
2  to  i.  The  piston  of  the  cylinder  seen  on  the  right,  which  is 
connected  to  the  slow  moving  shaft,  sweeps  a  less  volume  than 
the  other  does,  besides  making  only  half  the  number  of  strokes. 
This  smaller  volume  is  secured  either  by  shortening  the  crank  or 
lessening  the  diameter  of  the  cylinder,  or  by  the  two  combined. 
The  two  wheels  are  engaged  so  that  when  the  fast-moving  piston 
(on  left)  is  at  its  outer  and  inner  dead  points,  the  other  is  distant 
from  its  dead  points  by  a  distance  corresponding  to  a  motion  of 
about  45  degrees  of  its  crank,  an  amount  of  travel  corresponding 
roughly  to  one-seventh  of  the  whole  stroke.  This  piston  regulates 
the  firing  and  the  exhaust  by  having  the  firing  tube  inserted 
through  the  cylinder  at  about  one- seventh  of  its  stroke  from  the 
inner  dead  point,  and  having  ports  opening  from  the  cylinder  at 
the  outer  seventh.  Thus  only  one  valve  is  required,  namely,  an 
automatic  lift  valve  for  admitting  the  charge  of  gas  and  air,  and 
for  preventing  the  formation  of  a  partial  vacuum  in  the  cylinders 
when  the  engine  misses  an  explosion  by  being  governed.' 

By  this  clever  device  of  two  pistons  operated  by  cranks  geared 


334  The  Gas  Engine 

together  in  the  ratio  of  two  to  one,  the  Acme  engine  succeeded  in 
getting  a  considerable  range  of  expansion  beyond  that  given  by 
other  engines. 

Figs.  156,  157  and  158  are  respectively  side  elevation,  sec- 
tional plan  and  end  elevation  of  a  12  HP  nominal  engine. 
The  cylinder  i  is  open  at  all  times  to  the  cylinder  2  by  the 
wide  short  port  3,  and  the  piston  A  in  cylinder  i  makes  double 


FIG.  155. — Burl's  Compound  Otto  Engine. 

the  number  of  strokes  of  the  piston  E  in  the  cylinder  2.  The 
crank  A1  connects  to  the  piston  A,  and  the  crank  B1  to  the  piston 
B  ;  these  cranks,  as  will  be  seen,  have  separate  shafts,  which  are 
geared  together  by  the  toothed  wheels  c.  The  automatic  lift  valve 
4  admits  a  mixture  of  gas  and  air  to  both  cylinders  by  way  of 
the  port  5,  and  and  this  valve  4  is  supplied  with  gas  by  way  of 
the  valve  6  (fig.  156).  The  gas  valve  is  controlled  by  the  inertia 


Otto  Cycle  Gas  Engines 


335 


governor  7,  which  causes  the  blade  8  to  miss  the  gas  valve  stem  6 
when  it  is  necessary  to  cut  out  ignitions.  The  tube  igniter  9  opens 
into  the  cylinder  2,  and  is  uncovered  at  the  proper  time  for  ignition 


H 
2 
O 

1 


by  the  piston  B  ;  that  is  about  the  position  shown  in  the  drawing, 
the  piston  B  one- seventh  on  its  forward  stroke,  and  the  piston  A 
just  on  the  in-centre.  During  the  time  the  piston  A  is  making  its 
complete  out- stroke,  the  piston  B  has  moved  out  about  5  of  its 


336 


The  Gas  Engine 


stroke,  and  has  uncovered  the  ports  10,  which  are  the  exhaust 
ports.  These  ports  are  cylinder  ports  such  as  were  used  in  the 
Clerk  engine.  The  pressure  in  both  cylinders  then  falls  to 
atmosphere,  and  the  piston  A  makes  its  return  stroke,  while  the 
piston  B  is  uncovering  the  ports  10  and  covering  them  again.  The 


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piston  B  is  just  closing  the  ports  10  when  the  piston  A  completes 
its  exhausting  stroke,  and  the  next  out-stroke  of  A  draws  into  the 
cylinder  a  mixture  of  gas  and  air  by  way  of  the  automatic  lift 
valve  4,  and  when  the  out  charging  stroke  is  completed  the  piston 
B  covers  the  igniter  tube  port  and  does  not  uncover  it  till  com- 


Otto  Cycle  Gas  Engines 


337 


pression  is  completed.  It  is  easy  to  see  that  by  proportioning 
the  stroke  and  diameter  of  the  piston  B  to  that  of  A,  any  desired 
expansion  of  the  charge  may  be  obtained. 

I-ig.  159  is  a  diagram  from  the  cylinder  2,  while  fig.  160  is 
one  from  the  cylinder  i,  of  a  12  HP  engine  similar  to  the 
illustrations,  taken  by  Prof.  Jamieson  of  Glasgow.  The  results  of 
the  test  are  marked  under  the  diagram  fig.  160.  An  examination 
of  the  two  diagrams  shows  clearly  the  action  of  the  engine.  Com- 
pression begins  when  the  piston  B  has  nearly  reached  the  end  of 


j  m 


FIG.  158.— Burt's  Compound  Otto  Engine  (end  elevation). 

s  stroke  and  continues  while  the  piston  moves  out  from  a  to  b,  fig. 
59,  that  is  the  piston  A  is  compressing  its  charge  partly  into  the 
earance   space  at   the  end  of  its  cylinder  and  partly  into  the 
ylinder  2  by  way  of  the  port  3,  so  that  the  piston  B  is  running 
way  from  the  piston  A,  and  is  being  followed  up  by  the  compres- 
on.     At  b  the  charge  ignites  and  the  pressure  rises  to  the  same 
oint  in  both  cylinders,  the  piston  B  continues  to  move  out  and 
followed  by  the  piston  A,  which  piston,  however,  speedily  over- 
kes  it,  so  that  it  finishes  its  stroke  before  the  piston  B  moves  out 
nough  to  uncover  the  exhaust  ports  10  on  the  side  of  the  cylinder  ; 

z 


333 


The  Gas  Engine 


the  pressure  then  falls  to  atmosphere  very  gently,  as  shown  by 
the  drop  on  the  diagram  fig.  159  at  the  points  The  diagram 
fig.  1 60  looks  like  an  ordinary  Otto  diagram,  but  in  interpreting 
its  indications  the  diagram  fig.  159  must  be  duly  considered. 


60 


30 


a 


Nominal  HP,  12  ;  short  stroke  cylinder,  10"  diam.  x  n"  stroke  ;  spring  T 
max.  pressuie,  158  Ibs.  ;  pressure  before  ignition  at  b,  48  Ibs. 


per  Ib. 


FIG.  159.—  Diagram  from  Cylinder  2  Hurt's  Compound  Otto. 

According  to  Prof.  Jamieson's  test  of  April  8,  1892,  the  12  HP 
engine  gave  13  brake  HP  on  a  consumption  of  19-3  cb.  ft.  per 
brake  HP  per  hour  of  Glasgow  gas. 

Prof.   Rowden   made  a   test  of  a  smaller  engine   of  6  HP 
nominal  at   the   establishment   of  Messrs.    Herbert  Bros.,  corn 


Nominal  HP,  12  ;  long  stroke  cylinder,  ^\\l>  diam.  X2o"  stroke  ;  rev.  per  min.  160  ; 
brake  HP,  13  ;  consumpt.  per  BHP  hour,  19-3  cb.  ft.  ;  max.  pressure,  158  Ibs.  ; 
pressure  before  ignition,  48  Ibs.  ;  scale  of  spring,  T»o"  Per  lb. 

FIG.  1 60. — Diagram  from  Cylinder  I  Burt's  Compound  Otto. 

merchants,  Kennedy  Street,  Glasgow,  and  obtained  8*28  brake 
HP  on  a  consumption  of  17-3  cb.  ft.  of  gas  per  brake  HP 
hour,  the  faster  crank  running  at  170  revolutions  per  minute. 
The  *  Acme  Compound '  engine  may  therefore  be  taken  to  have 
consumed  about  19  cb.  ft.  of  Glasgow  gas  per  brake  HP  hour  ; 


Otto  Cycle  Gas  Engines  33^ 

this  corresponds  to  about  21  ch.  ft.  of  Birmingham  gas,  so  that 
the  results  are  very  creditable. 

General  Remarks.—  This  engine  has  been  replaced  by  the 
Messrs.  Burt's  Otto  engine  of  more  usual  type.  The  engine, 
although  called  compound,  was  not  really  a  compound  because 
both  cylinders  served  as  high  and  low  pressure  cylinders 
simultaneously.  It  seems  to  the  author  that  an  engine  cannot 
be  truly  termed  '  compound '  unless  it  includes  separate  high- 
pressure  and  low-pressure  cylinders.  The  advantages  to  be  ob- 
tained by  the  compound  engine  in  saving  weight  and  strength  of 
engine  cannot  be  gained  without  the  use  of  a  small  cylinder  to 
operate  at  high  pressure  and  a  large  cylinder  to  operate  at  low 
pressure.  This  engine  was  necessarily  heavy  for  its  power,  and  it 

180 


Nominal  HP,  6  ;  diam.  of  cylinder,  9*"  ;  length  of  stroke,  16"  ;  rev.  per  min.  180 ; 
cohsumpt.  per  IHP  hour,  15*03  cb.  ft.  ;  consumpt.  per  BHP  hour,  2o'8o8  cb.  ft.  ; 
scale  01  spring,  T|5"  per  Ib.  ;  max.  pressure,  171  Ibs.  ;  pressure  before  ignition, 

69  Ibs. 

FIG.  161.— Diagram  from  6  NHP  Burt's  Otto  Engine. 

had  the  great  disadvantage  of  requiring  gear  wheels,  which  wheels 
had  to  take  the  whole  strain  of  the  explosion. 

The  engine  is,  however,  very  clever  and  interesting,  and  the 
author  has  described  it  at  some  length  because  of  some  lessons  it 
teaches,  which  will  be  referred  to  in  a  later  chapter,  when  com- 
pounding is  discussed. 

Burfs  Otto  Engine. — Messrs.  Burt  &  Co.  now  manufacture 
Otto  gas  engines  of  more  usual  construction,  but  instead  of  the 
ordinary  lift  valves  they  adopt  a  piston  valve  driven  from  the 
valve  shaft  by  a  small  crank.  They  obtain  fair  results  with  those 
engines,  as  will  be  seen  from  diagram  fig.  161,  in  which  a  6  HP 
engine  shows  a  consumption  of  15 -03  cb.  ft.  of  Glasgow  gas  per 
IHP  hour,  and  20-8  cb.  ft.  per  brake  HP  hour.  It  is  to  be  kept 
in  mind  that  Glasgow  gas  is  of  higher  heat  value  than  moht 

z  2 


340 


The  Gas  Engine 


samples  of  English  gas,  but  it  is  not  so  high  now  (1895)  as  it  was 
in  1885,  as  the  standard  has  been  reduced. 


FIG.  162.— Burt's  High  Speed  Otto  Engine  (vertical  section). 

Messrs.  Burt  &  Co.  have  recently  built  a  high-speed  gas 
engine,  of  which  a  vertical  section  is  given  at  fig.  162,  which  is 
especially  interesting,  as  it  approaches  so  closely  to  steam  engine 


Otto  Cycle  Gas  Engines  341 

lines.  Two  pistons  i  and  2  are  arranged  tandem  fashion  on  the 
same  piston  rod  3  ;  a  common  connecting  rod  4  serves  for  both 
and  actuates  a  crank  5.  The  upper  sides  of  the  pistons  are  used 
for  the  power  impulses,  and  the  lower  sides  operate  idly  moving 
air  to  and  fro ;  both  pistons  operate  on  the  Otto  cycle,  but  the 
impulses  are  arranged  to  alternate.  The  crank  thus  gets  an 
impulse  at  every  revolution  when  the  engine  is  under  full  load. 
The  crank  shaft  carries  a  wheel  6  gearing  into  a  wheel  7,  from 
which  the  piston  valve  is  driven  at  half  the  number  of  strokes 
of  the  main  crank.  The  action  and  function  of  these  piston 
valves  are  very  peculiar.  The  pistons  i  and  2,  it  will  be  seen, 
approach  their  cylinder  covers  as  nearly  as  steam  engine  pistons, 
and  the  main  combustion  space  is  formed  by  the  ports  and  pas- 
sages leading  to  the  valves,  and  also  by  the  annular  space  formed 
between  the  piston  valve  stems  9  and  the  cylinder.  When  the 
upper  piston  i  is  in  the  position  shown  in  the  figure,  it  will  be  seen 
that  the  cylinder  is  open  to  the  annular  space  formed  round  the 
piston  valve  stem  9,  and  between  the  piston  ports  of  the  valve. 
These  spaces  form  the  combustion  chamber,  and  the  explosive 
mixture  is  compressed  into  them  and  ignited  by  the  tube  igniter 
10.  When  the  piston  i  has  made  its  power  stroke  down,  the 
piston  valve  moves  to  bring  into  connection  the  ports  n  and  12* 
and  the  piston  i  then  moves  up  and  discharges  the  exhaust  pro- 
ducts ;  on  the  next  down  stroke  the  piston  valve  again  takes  the 
position  shown  by  the  upper  valve,  and  the  lower  valve  13  is 
opened  to  admit  a  charge  of  gas  and  air  on  the  next  down  stroke. 
The  piston  2,  as  shown  on  the  drawing,  is  just  finishing  its  ex- 
hausting stroke,  and  the  piston  valve  is  about  to  close  the  exhaust 
port.  The  valve  arrangements  of  piston  2  are  similar  to  those  of 
piston  i. 

This  engine  is  most  interesting  for  many  reasons  ;  its  designers 
are  very  daring,  and  appear  to  the  author  to  disregard  some  of 
the  understood  conditions  of  gas  engine  economy.  It  appears  to 
him  impossible  to  obtain  any  high  economy  in  gas  consumption 
from  an  engine  with  its  combustion  spaces  made  up  of  tortuous 
ports  and  passages.  The  engine  gives  the  designer  an  extreme 
example  in  the  direction  of  subdividing  the  combustion  space, 
and  it  will  certainly  be  interesting  to  know  its  power  and  gas 


542 


The  Gas  Engine 


consumption.     Fig.   163  gives  diagrams  taken  from  the  top  and 
bottom,  cylinders  at  400  and  480  revolutions  respectively. 

Robey's  Otto  Engine.— Messrs.  Robev  &  Co.  now  build  Otto 
engines  up  to  a  brake  power  of  120  horse. 

"  Figure  164  shows  their  engine  as  made  from  36  brake  horse 


-200 


100 


ZO 


216 


Top  cylinder,  400  revs,  per  min. 


IS 


Bottom  cylinder,  480  revs,  per  min. 

FIG.  163. — Diagrams  from  Top  and  Bottom  Cylinders, 
Burt's  High  Speed  Engine 

to  120 ;  the  bed  of  the  engine  is  of  the  Corliss  type,  and  like  all 
this  maker's  engines  the  design  is  pleasing  and  workmanlike. 
The  exhaust  valve  opens  directly  into  the  combustion  chamber, 
and  so  avoids  port  clearance  spaces.  This  valve  is  removed  by 
lifting  a  cap  placed  on  the  upper  side  of  the  cylinder  and  pulling 
the  exhaust  valve  through,  after  removing  the  lever  connections. 


Otto  Cycle  Gas  Engines 


343 


344  'The  Gas  Engine 

The  charge  inlet  valve  opens  into  a  port  at  the  end  of  the  combus- 
tion chamber,  and  it  also  is  removed  by  way  of  a  cover  placed 
above  it.  This  system  avoids  the  use  of  heavy  sleeves  which 
require  'to  be  taken  out  from  below  :  such  sleeves  being  very 
inconvenient  in  large  engines. 

Ignition  is  effected  by  an  incandescent  tube,  controlled  by 
the  usual  timing  valve.  Messrs.  Robey  use  a  compression  pres- 
sure of  60  Ibs.  per  square  inch. 

Wells  Brothers'  Otto  Engine.— Messrs.  Wells  Brothers  build 
Otto  cycle  engines  up  to  1 20  HP.  They  make  their  engines  of  three 
main  types  ;  the  smaller  engines  up  to  and  including  16  nominal 
HP  are  made  on  the  usual  Otto  cycle  without  scavenging  ; 
engines  of  20  nominal  HP  and  above  are  made  with  a  scavenging 
arrangement  to  displace  the  exhaust  products.  The  front  end  of 
the  piston  is  enlarged  and  forms  an  annular  cylinder  which  serves 
as  an  air  pump.  On  the  return  stroke  the  air  is  discharged  from 
the  annulus,  and  passed  through  the  combustion  space  of  the 
cylinder  so  as  to  displace  the  burnt  gases  by  pure  air.  For 
ordinary  work  the  engine  is  made  with  a  single  cylinder,  but  for 
electric  lighting  two  cylinders  are  used  arranged  in  tandem. 
Fig.  165  shows  in  elevation  an  engine  of  the  tandem  type  capable 
of  indicating  120  HP  with  Dowson  gas.  The  engine  is  con- 
structed and  operates  as  follows.  The  front  motor  piston  has  a 
large  end  which  works  in  the  bored  bedplate ;  to  this  end  the 
connecting  rod  is  attached,  so  that  it  acts  as  a  guide  block.  Two 
side  rods  are  secured  to  the  end  and  passed  backwards  alongside 
the  cylinder  liner  through  a  passage  way  cast  in  the  water  jacket  : 
thence  they  pass  through  bushes  having  light  spring  rings  and 
secured  at  their  rear  ends  to  the  crosshead  of  the  back  piston.  The 
large  piston  acts  as  an  air  pump,  but  a  free  passage  to  the  atmo- 
sphere is  provided  during  the  first  part  of  the  back  stroke,  so  that 
the  air  intended  for  scavenging  is  only  compressed  and  passed 
through  the  combustion  chamber  towards  the  end  of  the  exhaust 
stroke.  As  the  cylinders  make  exhaust  strokes  alternately,  and 
the  large  piston  forces  air  through  the  air  passage  leading  to  both 
cylinders  at  every  back  stroke,  the  air  is  discharged  through 
whichever  of  the  motor  cylinders  is  in  its  exhaust  stroke. 

The  governor  is  of  the  high  speed  spring  loaded  centrifugal 


Otto  Cycle  Gas  Engines 


345 


i 


346  The  Gas  Engine 

type,  and  is  driven  by  a  bevil  wheel  on  the  crank  shaft ;  it  controls 
upright  hit  and  miss  rods  in  such  a  manner  that  the  gas  is  cut  out 
from  one  cylinder  before  the  other.  The  proportion  of  gas  ad- 
mitted is  also  varied  between  narrow  limits  by  graduated  notches, 
which  determine  the  lift  of  the  gas  valves.  The  engine  has  two 
flywheels  and  outside  adjustable  bearings,  positive  ratchet  feed 
lubricators  for  the  cylinders,  and  an  oil  box  on  the  splash  guard, 
and  sight  drop  feed  supply  to  the  main  bearings  and  to  the  crank 
pin  by  a  centrifugal  oiler.  This  engine  is  interesting,  and  it  gives 
economical  results.  Messrs.  Wells  have  supplied  the  author  with 
the  following  particulars  of  a  test  made  in  their  workshops  with 
Nottingham  coal  gas  : 

TEST  OF  A  60  BHP  WELLS  TANDEM  ENGINE. 

Diameter  of  cylinders 12  inches 

Stroke 18 

Speed        ........     164  revs,  per  min. 

i  front 82  per  min. 

Explosions -,back ;g        ^ 

Mean  effective  pressure 90  Ibs.  per  «q.  inch 

Load  on  brake  wheels 578  Ibs.  nett 

Circumference  brake  circle         .         ,         .         .22^3  feet 

Gas  consumption  per  hour        ....  1,190  cubic  feet 

Indicated  horse  power       .....  73*9 

Brake  horse  power 64-0 

Gas  per  IHP  per  hour       .         .         .         .     ,    .  i6'i  cubic  feet 

Gas  per  BHP  per  hour      .......  i8'6        ,, 

These  results  are  very  satisfactory,  and  prove  Messrs.  Wells' 
engine  to  be  an  economical  one. 

Fielding  &  Platfs  Otto  Engine.— Messrs.  Fielding  and 
Platt  build  Otto  cycle  engines  up  to  200  indicated  HP,  the  larger 
engines  being  of  the  tandem  type.  From  the  largest  engine  they 
obtain  170  brake  horse  power  at  full  load,  and  by  their  system  of 
governing  for  electric  light  purposes  they  claim  that  the  maximum 
speed  variation  between  running  light  and  full  load  does  not 
exceed  three  per  cent.  To  accomplish  this  the  engine  is  governed 
without  cutting  off  the  gas  ;  power  impulses  are  given  continuously, 
but  reduced  in  strength  to  meet  the  variation  in  load.  The  gas 
and  air  supply  valves  are  regulated  separately,  the  governor 
reducing  the  gas  and  air  simultaneously.  The  combustible  mixture 


Otto  Cycle  Gas  Engines  347 

supplied  to  the  engine  is  thus  kept  practically  constant  as  to  the 
relative  amounts  of  gas  and  air,  but  the  volume  supplied  is 
diminished  and  so  reduces  the  compression.  The  compression 
varies  from  about  5  Ibs.  above  atmosphere  to  60  Ibs.  and  ac- 
cordingly the  explosion  diagram  varies  within  wide  limits,  so 
wide  indeed  that  it  is  never  necessary  to  miss  impulses.  The 
consumption  is  of  course  increased  per  indicated  HP  for  light 
loads,  but  there  are  many  cases  where  such  increase  is  quite  per- 
missible. The  idea  is  one  worthy  of  consideration  where  great 
regularity  is  required. 

Self-starting  Gear. — Before  leaving  the  mechanism  of  the  Otto 
cycle  engines,  it  is  desirable  to  describe  shortly  the  starting  gears 
which  are  now  used  for  such  engines.  The  great  increase  in  the 
power  of  the  engines  manufactured  has  made  it  imperatively 
necessary  to  provide  starting  devices  which  dispense  with  the  old 
method  of  starting  by  hand. 

The  first  gas  engine  starting  gear  introduced  in  this  country 
was  the  invention  of  the  author,  and  was  applied  to  the  Clerk 
impulse-every-revolution  engine,  as  described  at  p.  239  of  the 
earlier  part  of  this  work.  That  starter  required  to  store  up  air  or 
gas  and  air  mixture  under  compression,  and  this  was'  found  to 
involve  expensive  arrangements,  so  that  although  the  gear  was 
quite  satisfactory  in  action  its  first  cost  was  too  high. 

The  starting  gear  now  the  most  extensively  used  is  also  the 
invention  of  the  author  ;  the  patent  has  been  acquired  by  the 
Messrs.  Crossley,  and  the  Clerk  starter  is  now  used  by  them  in 
all  engines  of  sufficient  dimensions  to  require  a  starter. 

Fig.  1 66  is  a  diagrammatic  section  illustrating  its  action.  A  is 
the  gas  engine  cylinder  ;  B  a  check  valve  opening  into  the  exhaust 
port  ;  D  a  chamber  connected  by  the  pipe  D1  to  the  valve  B  ;  and  i 
is  an  igniting  valve.  K  is  a  port  leading  to  a  charging  pump. 

The  object  of  the  device  is  to  fill  the  combustion  space  of  the 
engine  with  a  compressed  mixture  of  gas  and  air,  and  then  to 
explode  that  compressed  mixture  and  so  provide  a  high-pressure 
explosion  to  give  the  starting  impulse. 

To  start  :  the  engine  crank  is  placed  well  off  the  centre ;  the 
pump  is  operated  by  hand  to  fill  the  chamber  D,  pipe  D1  and 
cylinder  A  with  gas  and  air  mixture  at  atmospheric  pressure,  so  that 


348 


The  Gas  Engine 


no  resistance  is  experienced  during  the  operation  of  the  pump. 
After  charging,  the  igniter  is  operated,  and  the  mixture  in  the 
chamber  D  ignites  at  the  end  near  i  ;  the  flame  as  it  spreads 
through  the  chamber  forces  the  unburned  mixture  before  it  into 
the  pipe  D1  through  the  valve  B  into  the  cylinder  A,  so  that  when 
the  flame  arrives  at  the  valve  B  it  has  swept  before  it  into  the 
cylinder  all  the  unburned  mixture,  and  when  the  flame  passes  the 
valve  B  it  ignites  the  compressed  mixture  in  the  cylinder  and 
produces  a  high-pressure  explosion  which  starts  off  the  engine 
with  an  ample  margin  of  power  to  overcome  the  friction  of 
belting  and  shafting. 

In  conjunction   with    Mr.  F.   W.  Lanchester  the  author  has 


FIG.  1 66.  —  Clerk  Flame  Starter. 

produced  a  modification  of  this  starting  gear  which  is  known  as 
Clerk-Lanchester  starting  gear,  and  it  is  illustrated  in  diagrammatic 
section  at  fig.  167.  In  this  arrangement  the  igniting  valve  Y  is 
adopted,  which  is  the  invention  of  Mr.  Lanchester.  The  pump 
for  charging  the  starting  chamber  is  also  dispensed  with. 

The  action  is  as  follows  :  When  the  engine  is  stopping,  while  it 
is  making  the  last  few  revolutions  with  the  gas  turned  off,  the  valve 
w  is  opened  and  air  is  drawn  through  the  chamber  D  by  way  of 
the  valve  Y  at  every  suction  stroke.  The  chamber  D,  pipe  D'  and 
cylinder  A  thus  become  filled  with  pure  air  at  atmospheric 
pressure.  When  the  engine  is  to  be  started  the  gas  cock  F  is 
opened  and  gas  flows  from  the  gas  main  pipe  at  G  into  the  chain- 


Otto  Cycle  Gas  Engines 


349 


ber  D  and  at  H  into  the  pipe  D',  a  cock  on  the  cylinder  being 
opened  to  allow  flow  into  the  cylinder,  or  the  exhaust  valve  is  held 
slightly  open.  The  flame  x  burns  across  the  valve  Y,  and  after  a 
few  seconds  mixture  of  gas  and  air  escapes  through  Y  and  burns 
in  the  air.  The  cock  F  is  then  closed,  and  the  flame  shoots  back 
past  the  valve  Y,  and  so  ignites  the  mixture  within  D,  closing  the 
valve  Y  against  an  upper  face  by  the  force  of  the  explosion.  The 
flame  then  proceeds  along  D,  D'  into  the  cylinder  A,  firing  the  mix- 
ture it  has  compressed  before  it,  and  so  the  engine  is  started  by  a 
compression  explosion. 

Fig.  1 68  is  a  starting  diagram  obtained  from  this  arrangement. 


FIG.  167 Clerk-Lanchester  Starter  (diagrammatic  section). 

From  the  diagram  it  will  be  observed  that  a  maximum  pressure  of 
200  Ibs.  per  square  inch  is  attained,  giving  an  available  starting  pres- 
sure of  80  Ibs.  per  square  inch,  a  pressure  amply  sufficient  to  start  a 
gas  engine,  even  allowing  for  the  friction  of  a  line  of  shafting. 

The  great  advantage  of  the  Clerk  or  Clerk-Lanchester  starter 
is  due  to  the  ease  with  which  a  compression  explosion  is  obtained 
without  the  necessity  of  storing  up  compressed  gases  or  compress- 
ing gases  by  manual  labour. 

The  Lanchester  low-pressure  starter  is  also  extensively  used 
when  it  is  not  considered  necessary  to  obtain  a  high-pressure  ex- 
plosion. Fig.  169  is  a  diagrammatic  section  of  this  starter,  and 
fig.  170  is  an  indicator  diagram  showing  the  first  and  succeeding 


350 


The  Gas  Engine 


starting  explosions.  The  Lanchester  low-pressure  starter  is  un- 
doubtedly the  simplest  gas  engine  starting  device  which  has  ever 
been  produced.  It  requires  no  addition  to  the  engine  save  a  gas 
admission  cock  and  jet,  and  a  mixture  sampling  and  igniting  cock. 


200 


ISO 


100 


50 


FIG.  168. — Clerk  Starter  Diagram.    Initial  pressure,  200  Ibs.  per  sq.  in. 
Average  available  pressure,  80  Ibs. 

The  engine  cylinder  A  has  mounted  upon  it  the  sampling  and 
igniting  cock  i  shown  on  a  larger  scale  in  section  at  2  ;  the  cylinder 
is  also  supplied  with  a  gas  admission  jet  3,  fitted  with  a  cock. 


FIG.  169. — Lanchester  Starter  (diagrammatic  sections). 

When  the  gas  is  shut  off  to  stop  the  engine  the  cylinder  is  filled  with 
pure  air,  and  so  it  remains  filled  with  air  at  atmospheric  pressure. 
When  the  engine  is  to  be  started,  the  crank  is  set  well  above  the 
centre,  the  cock  3  is  opened  to  the  gas  supply,  the  cock  i  is  also 


Otto  Cycle  Gas  Engines 


351 


opened  and  the  jet  4  is  lit ;  the  gas  then  flows  into  the  cylinder  A, 
mixing  with  the  air  in  the  cylinder  and  displacing  some  air  through 
the  valve  chamber  B  (section) ;  in  this  chamber  B  is  fitted  a  double- 
seated  valve,  which  usually  by  its  weight  rests  upon  the  lower  seat ; 
grooves  are  cut  round  it  and  along  its  lower  face  to  allow  gases  to 
flow  past  it  while  it  rests  on  its  lower  seat.  When  the  gas  jet  is 
first  turned  on  air  only  flows  through,  but  after  a  few  seconds  gas 
mixture  follows  and  is  ignited  by  the  jet  4.  The  mixture  burns  as 
shown,  and  as  it  becomes  richer  in  gas  the  flame  changes  its 
colour  and  burns  with  a  sharp  roar  ;  the  cock  3  is  then  turned  off, 
and  the  flame  shoots  back  into  the  cylinder  and  ignites  the  mix- 
ture existing  at  atmospheric  pressure  within  it.  The  explosion  at 
once  slams  the  valve  B  against  its  upper  seat  and  so  closes  it.  The 
engine  then  starts  under  the  pressure  of  the  low-pressure  explosion. 


FIG.  170. — Lanchester  Starter  Diagrams. 

At  fig.  1 70  the  diagram  a  shows  the  first  explosion,  and  it  will  be 
observed  that  other  diagrams  b  follow  the  first  explosion.  These 
explosions  are  produced  by  the  action  of  the  igniter.  When 
the  engine  moves  by  the  first  explosion,  the  piston  on  its  return 
discharges  the  exhaust  in  the  usual  manner  ;  on  the  next  out-stroke 
it  takes  in  the  usual  charge  of  gas  and  air.  On  the  next  return 
stroke,  however,  which  would  be  the  ordinary  compressing  stroke, 
the  exhaust  valve  is  held  open  during  the  whole  stroke,  and  so  the 
combustion  space  is  left  at  the  end  of  the  stroke  filled  with  a 
mixture  of  gas  and  air  under  no  compression.  During  this  back 
stroke  some  of  the  mixture  flows  through  the  jet  i,  and  is  ignited  at 
the  flame,  and  so  soon  as  the  piston  begins  to  move  out  again  the 
flame  shoots  back,  and  another  low-pressure  explosion  occurs, 
as  shown  at  ^,  fig.  170.  In  this  manner  a  series  of  low-pressure 


352  The  Gas  Engine 

explosions  are  obtained  sufficient  to  get  up  the  speed  of  the  engine 
to  a  point  at  which  the  compression  may  be  safely  applied  and  the 
engine  caused  to  perform  its  ordinary  cycle.  The  Lanchester 
starter  is  much  used,  and  is  very  successful  when  the  friction  of 
the  engine  and  its  connections  is  not  too  great. 

Other  Self -starting  Devices. — The  Lanchester  and  Clerk  starters 
may  be  taken  as  the  typical  starters  of  to-day,  and  they  are  applied 
much  more  extensively  than  any  other  types.  Most  makers, 
however,  now  supply  with  their  engines  self-starters  of  some  kind. 

Messrs.  T.  B.  Barker  &  Co.  and  Messrs.  Robey  &  Co.  use  the 
Lanchester  starter.  Messrs.  J.  E.  H.  Andrew  &  Co.  also  employ 
a  low-pressure  starter  which  resembles  Lanchester's  in  its  leading 
features.  The  igniting  device  is  connected  with  the  ordinary 
igniter  tube.  Fig.  138,  page  320,  shows  this  arrangement  in  section. 
The  igniter  tube  c  is  fitted  with  an  internal  directing  tube 
communicating  behind  the  timing  valve  F.  A  gas  supply  cock 
with  its  jet  somewhat  similar  to  3,  fig.  169,  is  applied  to  the  engine 
cylinder.  When  it  is  desired  to  start,  the  engine  crank  is  set  well 
off  the  centre  as  usual,  the  tube  c  is  heated  to  incandescence  and 
the  valve  A  fig.  138  is  opened  to  the  atmosphere.  The  valve  F 
is  also  opened  in  towards  the  cylinder.  Gas  then  flows  into  the 
cylinder,  mixes  with  the  air  within  it  as  with  the  Lanchester 
device,  and  in  entering  it  displaces  air  first  and  inflammable  mixture 
afterwards  past  the  valve  F  up  the  internal  directing  tube  into  the 
igniter  tube  c,  then  away  in  the  direction  shown  by  the  arrows  to 
the  valve  A  and  past  that  valve  to  the  atmosphere.  When  the 
mixture  becomes  inflammable  enough,  the  gas  supply  is  cut  oft" 
and  the  igniter  tube  ignites  the  mixture,  then  the  valve  A  closes 
upon  explosion.  By  this  neat  device  Messrs.  Andrew  obtain  their 
low-pressure  starting  explosion.  The  whole  arrangement  resembles 
Lanchester's  except  in  the  rather  neat  device  for  utilising  the  ordinary 
igniter  tube  c  to  obtain  the  starting  explosion  as  well  as  the 
ordinary  explosions. 

Messrs.  Tangye  adopt  a  somewhat  more  complex  method  of 
starting  ;  they  set  the  engine  crank  on  the  in-centre,  then  pump  a 
mixture  of  gas  and  air  into  the  cylinder  till  the  pressure  approaches 
the  usual  pressure  of  compression  ;  they  then  simultaneously  move 
the  crank  off  the  centre  and  admit  the  compressed  charge  to  the 


Otto  Cycle  Gas  Engines  353 

igniter.  They  thus  start  with  a  compression  explosion.  This 
starter,  it  appears  to  the  author,  is  open  to  the  objection  that  in 
the  event  of  a  slight  leak  in  the  piston  the  man  operating  the  hand 
pump  may  be  unable  to  pump  fast  enough  to  obtain  the  necessary 
compression. 

Messrs.  Fielding  &  Platt  utilise  a  starter  which  in  one  feature 
resembles  the  old  Clerk  starter  described  on  p.  239.  They  cause 
the  engine  to  compress  air  into  a  reservoir  to  a  pressure  of  about 
60  Ibs.  per  sq.  inch  and  store  this  pressure  up  till  wanted.  To  start, 
the  engine  is  put  off  the  centre  and  the  cylinder  is  filled  with  pure  gas 
or  a  mixture  at  atmospheric  pressure  so  rich  in  gas  that  it  is  non- 
explosive.  The  air  under  pressure  is  then  admitted  to  the  cylinder 
and  forms  an  explosive  mixture  under  pressure,  which  mixture  is 
ignited  in  the  usual  way  by  an  igniter  tube  to  give  the  starting 
explosion. 


A  A 


354  The  Gas  Engine 


CHAPTER  III. 

THE    PRODUCTION    OF    GAS    FOR    MOTIVE    POWER. 

IT  has  been  already  pointed  out  by  the  author  in  the  earlier  part 
of  this  work,  that  the  unit  of  heat  supplied  in  the  form  of  ordinary 
coal  gas  is  more  costly  than  the  unit  of  heat  supplied  in  the  form 
of  coal,  and  that  accordingly  the  gas  engine  remains  at  a  disadvan- 
tage as  compared  with  the  steam  engine  till  the  time  comes  when 
the  gas  unit  of  heat  costs  no  more  than  the  coal  unit.  This  fact 
has  been  recognised  by  many  inventors,  and  numerous  attempts 
have  been  made  to  produce  cheaper  gas.  Mr.  J.  E.  Dowson, 
however,  is  the  only  inventor  who  has  made  much  headway  in  this 
subject,  and  his  producers  are  now  largely  employed  for  generating 
gas  for  gas  engines  of  large  powers.  Mr.  Dowson  has,  however,  only 
effected  a  partial  solution  of  the  problem,  as  his  producers  can  only 
use  two  kinds  of  fuel,  anthracite  and  coke.  Of  the  two  his  pro- 
ducer acts  better  with  anthracite  ;  with  coke  its  performance  cannot 
be  said  to  be  entirely  satisfactory.  The  disadvantage  of  more 
expensive  heat  unit  is  not  felt  in  small  gas  engines,  because  the 
governing  of  the  engine  and  the  heat  efficiency  is  so  much  superior 
to  any  small  steam  engine  that  even  in  actual  expense  of  fuel  the 
gas  engine  is  superior.  The  attendance  required  is  also  trifling 
compared  with  the  steam  engine.  Accordingly  it  is  quite  un- 
necessary to  trouble  about  gas  other  than  towns  gas  for  engines 
under  twenty  horse  power.  Engines  giving  out  that  power  or  any 
power  above  that  and  working  steadily  at  full  load  require  cheaper 
gas  to  compete  with  the  steam  engine.  It  would  not  be  difficult, 
for  example,  to  work  a  steam  engine  giving  100  horse  power  at 
3  Ibs.  of  coal  per  IHP  hour,  the  coal  costing  not  more  than  los. 
per  ton  ;  this  gives  an  expenditure  for  coal  of  0-16  penny  per  HP 


TIu  Production  of  Gas  for  Motive  Power  355 

hour.  A  gas  engine  of  100  horse  power  would  use  about  ij  Ib.1 
of  anthracite  costing  205-.  per  ton,  and  here  the  fuel  would  cost 
0-15  penny  per  HP  hour.  That  is,  assuming  that  the  gas  engine 
and  producer  cost  as  much  for  attendance,  repairs  and  oil  as  the 
steam  engine  and  boiler  of  corresponding  power,  it  would  just 
compete  favourably  with  a  steam  engine  using  3  Ibs.  of  coal 
per  indicated  horse  power.  The  gas  engine,  however,  has  a  con- 
siderable advantage  even  when  supplied  by  gas  producers  in 
working  at  light  loads,  and  its  consumption  at  such  loads  is 
proportionately  less  than  the  steam  engine.  If,  however,  gas 
producers  could  be  made  which  would  effectively  produce  gas 
from  cheaper  fuel,  or  fuel  such  as  the  slack  generally  used  for 
steam  boilers,  then  the  gas  engine  would  have  an  overwhelming 
superiority  over  the  steam  engine  from  a  pecuniary  point  of  view 
in  large  engines  as  well  as  small. 

The  gas  producer  problem  is,  therefore,  one  which  will  doubt- 
less very  considerably  exercise  the  attention  of  inventors.  Accord- 
ingly the  author  will  now  shortly  discuss  the  principles  of  the 
subject,  and  then  describe  the  Dowson  and  another  producer  and 
some  of  their  difficulties. 

Ordinary  town  illuminating  gas  is  produced  by  the  destructive 
distillation  of  suitable  coal.  The  object  of  the  manufacturer  is  to 
produce  a  gas  capable  of  burning  with  a  bright  illuminating  flame. 
It  is  a  purely  accidental  circumstance  that  such  illuminating  gas 
has  also  been  found  very  suitable  for  generating  motive  power. 
Accordingly,  it  is  not  to  be  expected  that  coal  gas  should  be  gene- 
rated under  the  best  economic  conditions  for  cheap  motive  power. 
Gas-making  coal  is  necessarily  more  expensive  than  the  fuel 
ordinarily  used  in  steam  boilers,  and  further  the  process  of  destruc- 
tive distillation  can  only  liberate  from  the  coal  such  volatile 
matters  as  enter  into  its  composition.  The  amount  of  gas  so 
obtained  per  ton  of  coal  depends  on  the  temperature  of  distillation, 
or  the  temperature  of  carbonisation  as  the  gas  engineers  call  it. 
At  a  comparatively  high  temperature  a  larger  volume  of  gas  is  given 
off  per  ton,  but  the  percentage  of  illuminating  gases  present  are 
reduced,  and  so  the  illuminating  power  is  low.  A  good  gas  coal 
on  destructive  distillation  will  yield  at  a  fair  carbonising  temperature 

1  Under  i  Ib.  per  IHP  hour  has  been  claimed  by  Mr.  Dowson. 

A  A  2 


356  The  Gas  Engine 

from  10,000  to  11,000  cb.  ft.  of  gas  per  ton  of  coal  of  from  15 
to  17  candle  power,  and  it  will  leave  in  the  retort  about  62  to  73 
per  cent,  of  coke  ;  that  is,  of  100  tons  of  the  original  gas  coal  38 
to  27  tons  are  driven  off  as  illuminating  gas,  vapour,  tar,  ammonia, 
water,  &c.,  while  62  to  73  tons  remain  in  the  retort  as  coke.  So 
long,  then,  as  the  ordinary  process  of  destructive  distillation  is 
adopted,  the  heat  unit  of  coal  gas  supplied  to  a  gas  engine  must 
necessarily  be  more  expensive  than  the  heat  unit  evolved  in  the 
furnace  of  a  steam  boiler,  because  more  fuel  and  that  more  expen- 
sive fuel  is  required  apart  altogether  from  the  cost  of  the  distribu- 
tion of  the  gas  from  the  gas  works.  To  compete  with  the  steam 
boiler  and  furnace  in  producing  a  gas  heat  unit  as  cheaply  as  a 
coal  heat  unit  placed  on  the  fire  grate,  it  is  necessary  to  convert 
the  whole  of  the  coal  into  gas  suitable  for  use  in  a  gas  engine. 

At  first  glance  it  appears  a  difficult  problem  to  produce  inflam- 
mable ?as  from  solid  carbon  either  in  the  form  of  anthracite  or  of 

O 

coke,  but  the  principle  is  simple  enough.  When  unit  weight  of 
carbon  is  entirely  burned  in  air  or  oxygen,  carbonic  acid,  or  more 
properly  carbonic  anhydride,  is  formed,  that  is  the  gas  CO,.  This 
gas  CO  2  if  passed  through  a  sufficient  depth  of  incandescent  carbon 
is  converted  into  the  gas  carbonic  oxide,  which  is  inflammable.  The 
chemical  reaction  is  generally  given  : 


That  is,  two  volumes  of  CO.,  combined  with  a  sufficient  weight 
of  carbon  to  form  carbonic  oxide  produce  four  volumes  of  carbonic 
oxide  gas.  For  the  purpose  of  the  gas  engine  using  a  properly 
proportioned  gis  generator  it  may  be  considered  that  the  carbon 
used  is  burned  to  carbonic  oxide  only  and  not  to  carbonic  acid. 
The  heat  evolved  in  the  process  of  producing  carbonic  oxide 
from  carbon  is 

Unit  weight  of  carbon  forming  CO   evolves  2400  heat  units, 

but 

Unit  weight  of  carbon  forming  COo  evolves  8000  heat  units, 

so  that  the  process  of  the  formation  of  carbonic  oxide  loses  a  part 
of  the  heat  of  the  carbon,  and  the  same  weight  of  carbon  in 
carbonic  oxide  will  only  produce  when  the  carbonic  oxide  is 
burned  5,600  heat  units  instead  of  8,000.  Thus  by  passing  air 


The  Production  of  Gas  for  Motive  Power  357 

through  incandescent  carbon  or  coke  of  a  sufficient  depth,  carbonic 
oxide  gas  can  be  formed  and  the  whole  of  the  carbon  transformed 
into  an  inflammable  gas.  The  air  on  first  coming  into  contact 
with  the  incandescent  carbon  burns  a  portion  of  it  to  CO2,  carbonic 
acid  gas,  and  this  carbonic  acid  on  passing  through  a  further  body 
of  incandescent  carbon  is  reduced  to  the  inflammable  gas  carbonic 
oxide,  CO.  The  first  stage  of  the  process  evolves  all  the  heat  of 
combustion,  and  the  second  stage  absorbs  a  portion  of  the  heat 
so  evolved.  The  net  result  is  that  if  the  inflammable  gas  produced 
be  cooled  down  and  then  burned  in  a  gas  engine  cylinder,  the  heat 
evolved  by  the  combustion  will  only  be  70  per  cent,  of  the  heat 
which  the  solid  carbon  would  have  evolved  if  burned  directly  with- 
out preliminary  conversion  into  gas.  The  30  per  cent,  of  heat  is 
carried  away  by  the  carbonic  oxide  from  the  gas  producer,  and  is 
lost  on  cooling  down  the  gas  to  suit  it  for  use  in  the  gas  engine. 
When  air  is  blown  through  the  producer  the  nitrogen  of  the  air  of 
course  remains,  and  is  mixed  with  the  inflammable  CO.  This  is 
the  fundamental  idea  of  the  gas  producer,  and  accordingly  it  will 
be  found  that  the  earlier  and  abortive  proposals  for  the  conversion 
of  the  entire  solid  fuel  into  gas  contemplated  only  blowing  air 
through  a  sufficient  depth  of  carbon.  Taking  the  composition  of 
atmospheric  air  as  4  vols.  nitrogen  and  i  vol.  oxygen  (the  new 
element  argon  may  be  neglected,  as  it  is  included  in  the  nitrogen 
and  is  very  similar  to  it),  then  the  best  gas  which  could  be  produced 
in  this  simple  manner  would  be  that  in  which  the  whole  of  the 
oxygen  was  used  up  in  forming  carbonic  oxide.  Remembering 
that  i  vol.  of  oxygen  gas  after  combining  with  enough  carbon  to 
make  CO  forms  2  vols.  of  that  gas,  the  composition  of  the  gas 
proceeding  from  the  producer  would  be  4  vols.  nitrogen  and 
2  vols.  carbonic  oxide,  that  is  : 

4  vols.  nitrogen  =  66*6  per  cen 

2  vols.  carbonic  oxide  =  33*3         , , 

100 'O 

The  gas  obtained  would  consist  entirely  of  66'6  per  cent,  of 
nitrogen  and  33-3  per  cent,  of  carbonic  oxide  ;  this  gas  on  com- 
bustion in  the  engine  would  evolve  70  per  cent,  of  the  heat  of  the 
original  carbon.  That  is,  if  the  efficiency  of  the  producer  be 
compared  with  a  steam  boiler,  it  would  be  equal  to  that  of  a  boiler 


358  The  Gas  Engine 

giving  70  per  cent,  of  the  heat  of  combustion  in  its  furnace  in  the 
form  of  steam  delivered  at  the  stop  valve. 

Such  a  producer,  however,  would  waste  an  entirely  unneces- 
sary amount  of  heat,  and  would  give  considerable  practical  difficulty 
in  getting  rid  of  the  30  per  cent,  of  the  heat  of  all  the  carbon 
gasefied  in  it,  the  lining  would  be  overheated,  and  generally  the 
temperature  of  the  carbon  contained  in  the  producer  would  be- 
come undesirably  intense.  A  certain  high  temperature  is  required, 
it  is  true,  to  convert  the  CO2  into  CO,  but  if  that  temperature  be 
maintained  it  is  undesirable  to  go  above  it.  Gas  engineers  have 
accordingly  taken  advantage  of  another  chemical  reaction  to  use 
some  of  this  heat  and  produce  better  gas.  If  steam  be  passed  over 
highly  incandescent  carbon,  which  carbon  must,  however,  be  kept 
incandescent,  the  oxygen  of  the  steam  unites  with  the  carbon,  and 
the  hydrogen  of  the  steam  is  liberated.  The  ultimate  effect  of  the 
reaction  is  to  decompose  steam  and  produce  hydrogen  and  carbonic 
oxide  ;  the  reaction  is  as  follows  : 


That  is,  2  volumes  of  water  vapour  in  contact  with  incandescent 
carbon  produce  2  volumes  of  hydrogen  gas  and  two  volumes  of 
carbonic  oxide  gas.  This  reaction,  however,  absorbs  heat  to  pro- 
duce the  decomposition  of  the  steam  ;  more  heat  requires  to 
be  absorbed  than  is  given  out  by  the  burning  of  the  carbon 
to  CO. 

To  decompose  steam  containing  2  units  weight  of  hydrogen 
gas  requires  the  absorption  of  68340  heat  units,  and  in  producing 
28  units  weight  of  CO  from  12  units  weight  of  carbon  there 
are  evolved  28800  heat  units  :  that  is,  the  heat  evolved  by  the 
carbonic  oxide  produced  in  the  reaction  is  about  one-half  of  the 
total  heat  required.  This  reaction  cannot  therefore  proceed 
without  a  sufficient  supply  of  heat  from  some  source  ;  the  best 
source  is  the  formation  of  CO  by  means  of  air  also  acting  on  the 
carbon.  To  supply  heat  just  sufficient  to  perform  the  reaction 
would  require  the  heat  evolved  in  producing  i  vol.  CO  by  air  and 
carbon  to  every  073  vol.  of  CO  produced  by  the  reaction  of 
steam  on  carbon.  The  composition  of  the  gas  so  produced 
would  be  : 


The  Production  of  Gas  for  Motive  Power  359 

CO  =  2       vote.  }  produced  by  the  reaction  of  the  oxygen  of  the  air  on  carbon. 
H~  J.46  ™j*'  }  produced  by  the  reaction  of  steam  upon  carbon. 

8-92  vols.  total. 
The  percentage  composition  would  be  about  : 

N=  45-0 

C0=  39-0 

H=   16-0 

JOO'O 

The  production  of  a  gas  of  this  composition  assumes  that  all  the 
heat  is  utilised  for  the  purpose  of  the  reaction  and  that  none  is 
lost  from  the  apparatus.  It  assumes  also  that  all  the  heat  carried 
away  by  the  gas  after  formation  is  returned  to  the  air  and  steam 
which  are  about  to  perform  the  reaction.  This  is  of  course  im- 
possible, but  the  calculation  has  been  made  in  order  to  supply  a 
standard  of  comparison.  Such  a  gas  would  contain  the  whole  of 
the  heat  of  the  original  carbon  before  gasefying.  In  an  actual 
apparatus  the  carbon  is  placed  in  a  brick-lined  producer  i-gnited  and 
blown  up  to  a  good  heat  by  a  forced  draught  ;  the  producer  is 
then  closed,  and  steam  and  air  blown  in  in  definite  proportions  to 
pass  through  the  incandescent  carbon  mass.  The  resulting  gas 
passes  away  from  the  producer  in  a  heated  state  and  is  cooled 
before  being  sent  into  the  gas  holder.  The  reaction  requires  a 
certain  temperature  for  its  continuance,  so  that  the  interior  of  the 
producer  must  not  fall  below  it  ;  the  gas  is  discharged  at  this 
temperature,  and  so  a  greater  supply  of  air  is  necessary  than  that 
calculated  to  make  up  for  the  heat  losses. 

Doivson  Gas  Producer. — The  Dowson  gas  producer  at  present 
embodies  in  the  best  way  the  fundamental  principles  and  the  con- 
structive details  necessary  for  the  production  of  gas  from  solid  fuel ; 
that  is,  gas  suitable  for  a  gas  engine. 

Fig.  171  is  a  diagrammatic  section  of  a  Dowson  gas  producer 
with  its  accompanying  gas  holder.  Fig.  172  is  an  elevation  part 
section,  and  fig.  1 73  a  plan  of  a  gas  producer  in  its  building  with 
all  the  necessary  parts  to  form  a  complete  plant. 

Referring  to  fig.  171,  the  producer  consists  of  a  cylindrical 
casing  A  lined  with  fire  brick  or  fire  clay,  and  having  at  the 


360 


The  Gas  Engine 


bottom  fire  bars  a  above  a  closed  ash  pit  B  ;  the  upper  part  of  the 
generator  is  closed  by  a  metal  plate  on  which  there  is  mounted  a 
fuel  hopper  A1  having  an  internal  bell  valve  a1  operated  from  the 
exterior.  To  begin  operations,  the  upper  cover  is  removed  from 


i i 


FIG.  171.— Dowson  Gas  Producer  and  Gas  Holder 
(diagrammatic  section). 

the  hopper  A1  and  the  bell  valve  is  opened  ;  a  fire  is  built  upon 
the  bars  a  and  air  forced  through  it  by  the  steam  jet  n  and  the 
pipe  N1  ;  fuel  (anthracite  or  coke)  is  slowly  added  from  above  till 
the  whole  mass  is  incandescent  and  fills  the  producer  to  a  depth 


The  Production  of  Gas  for  Motive  Power  361 

of  about  1 8  inches  at  least.  During  this  heating  up  process,  gases 
are  given  off  by  way  of  the  open  hopper,  and  they  are  ignited 
there  by  means  of  a  flame.  Great  care  must  be  taken  not  to 
inhale  the  issuing  gas,  as  it  contains  large  quantities  of  carbonic 
oxide  and  is  very  poisonous  ;  it  should  always  be  ignited  when  it 


FIG. 


SECTIONAL       ELEVATION- 

172. — Dowson  Gas  Producer  (part  in  section). 


flows  into  the  producer  room,  as  when  burned  it  becomes  harm- 
less. When  the  fuel  is  quite  incandescent,  the  inner  and  outer 
valves  of  the  hopper  are  closed  and  the  gas  flows  by  a  pipe 
through  cooling  and  scrubbing  devices,  finally  finding  its  way  into 
the  gas  holder  K  through  the  coke  scrubber  formed  within  it. 
From  the  gas  holder  the  gas  flows  through  another  scrubber,  ay- 


362 


The  Gas  Engine 


shown  by  the  arrow,  fig.  171,  and  thence  passes  to  the  engine. 
The  gas  holder  K  is  of  usual  construction  with  annular  water  seal 
and  balance  weights,  chains  and  pulleys. 

The  complete  plant  for  80  HP  effective  is  shown  at  figs. 
172  and  173,  where  A  is  the  small  steam  boiler  fitted  with 
superheating  tubes,  which  boiler  supplies  superheated  steam  to 
operate  the  air  injector  p.  and  so  forces  a  mixture  of  steam  and  air 


GENERAL        PLAN. 

FIG.  173. — Dowson  Gas  Producer  (plan). 

through  the  incandescent  fuel  contained  in  the  gas  generator  c. 
Fuel  is  fed  to  the  generator  by  the  feeding  hopper  D,  and  the  gas 
formed  flows  from  the  upper  part  of  the  producer  in  the  direction 
shown  by  the  arrow  to  the  gas  cooler  F,  whence  it  passes  to  the 
hydraulic  box  H,  which  box  is  provided  with  an  overflow  I,  and 
thence  the  gas  proceeds  to  the  sawdust  scrubber  j,  and  then  to 
the  coke  scrubber  K  contained  within  the  base  of  the  gas  holder. 
In  these  figures,  E  is  the  generator  fire  grate,  L  the  gas  holder,  M 


The  Production  of  Gas  for  Motive  Pozver  363 

the  outlet  from  the  gas  holder,  NN  the  ash  pit  for  the  generator, 
and  o  the  automatic  regulator  to  govern  the  production  of  gas  by 
stopping  or  reducing  the  supply  of  steam  with  the  upward  move- 
ment of  the  gas  holder. 

From  this  description  it  will  be  seen  that  the  whole  plant  is 
very  simple,  and  the  author  can  say  from  his  own  experience  that 
it  is  easily  operated  and  requires  little  repair.  One  man  can  easily 
attend  to  an  80  HP  plant. 

The  gas  produced  from  the  Dowson  producer  is  thus  a 
mixture  of  carbonic  oxide,  hydrogen,  and  nitrogen  ;  if  all  the 
actions  were  carried  out  perfectly  there  would  be  no  carbonic  acid 
gas  present,  but  as  all  the  actions  are  not  quite  up  to  theory  some 
carbonic  acid  is  formed.  A  little  sulphuretted  hydrogen  is  also 
formed,  more  with  coke  than  with  anthracite,  and  this  has  to  be 
removed,  as  sulphur  in  quantity  would  in  time  act  on  the  engine 
parts. 

The  following  analysis  of  Dowson  gas  was  made  by  Prof. 
Wm.  Foster ;  the  anthracite  used  in  the  producer  was  of  the 
cheapest  kinds  in  small  pieces  : 

Standard 

Analysis  of  Dowson  gas,  by  volume  gas 

(ideal) 

Nitrogen,  N 48-98         .  .         .       45-0 

Carbonic  oxide,  CO   .         .         .         .       25*07.       .         .         .  39-0 

Hydrogen,  H 1873) 

Marsh  gas,  CH4          .         .         .         .  -31  j*1 

Olefiant  gas,  C3H4      ....  -31 

Carbonic  acid,  COg             »  6*57 

Oxygen,  O '03 


Comparing  this  with  a  perfect  producer  gas,  it  is  seen  that 
instead  of  getting  39  per  cent,  of  carbonic  oxide  by  volume  only 
25-07  is  obtained  ;  on  the  other  hand,  when  the  ideal  gas  would  only 
give  16  per  cent,  of  hydrogen  1873  per  cent,  has  been  obtained, 
and  a  further  0*62  per  cent,  of  marsh  gas  and  olefiant  gas.  The 
marsh  gas  and  olefiant  gas  are  produced  doubtless  from  the  small 
quantity  of  hydrogen  which  forms  part  of  the  original  anthracite  ; 
anthracite  contains  about  3  per  cent,  of  hydrogen.  The  excess  of 
hydrogen,  however,  in  the  gas  can  only  arise  from  the  fact  that  the 
whole  of  the  carbonic  acid  originally  formed  is  not  reduced  to 


364  The  Gas  Engine 

carbonic  oxide.  This  is  evident  from  the  fact  that  6*57  per  cent,  of 
carbonic  acid  is  present.  As  the  burning  of  carbon  to  carbonic 
acid  instead  of  to  carbonic  oxide  involves  the  evolution  of  the 
whole  100  per  cent,  of  the  heat  of  combustion  of  the  carbon  instead 
of  only  30  per  cent,  of  it,  it  follows  that  more  heat  is  left  available 
for  the  decomposition  of  water  by  the  coke,  less  carbonic  oxide 
is  formed  by  the  action  of  the  oxygen  of  the  air  on  the  carbon, 
and  so  the  proportion  of  carbonic  oxide  in  the  gas  diminishes, 
while  that  of  hydrogen  increases.  A  French  analysis  of  Dowson 
gas  is  as  follows  : 

ANALYSIS  OF  DOWSON  GAS  PRCDUCED  IN  FRANCE. 

Nitrogen,  N         .         .         .  42  '28 

Carbonic  oxide,  CO     .         .         .     i8'2o\ 

Hydrogen,  H       .  .         .     26-55  I  45-86  combustible. 

Hydrocarbons,  \  CH4  I       .         .       I'll] 
i  CoH^  ) 

Carbonic  acid,  CO%     .         .         .     11*30 
Oxygen        .....       0-47 

Here  it  will  be  observed  that  the  nitrogen  is  still  lower,  and 
that  notwithstanding  the  great  increase  of  carbonic  acid  gas,  11*3 
per  cent,  instead  of  6-57  per  cent.,  the  hydrogen  gas  has  increased 
from  1873  Per  cent-  to  26-55  Per  cent.,  while  the  carbonic  oxide 
has  gone  down  from  25-07  per  cent,  to  18-20.  This  disproportion 
between  the  hydrogen  and  carbonic  oxide  can  only  arise  from  the 
fact  that  carbonic  oxide  itself  at  a  high  temperature  decomposes 
steam,  so  that  part  of  the  carbonic  oxide  which  would  otherwise 
have  appeared  in  the  mixture  has  disappeared,  forming  carbonic 
acid  and  hydrogen  ;  the  reaction  is  : 


That  this  is  true  is  evident  from  both  analyses,  where  there  is 
present  a  considerable  proportion  of  carbonic  acid,  in  one  case 
6-57  percent,  and  in  the  other  11-30  per  cent;  it  is  to  be  observed 
that  the  increase  of  hydrogen  is  accompanied  by  an  increase  of 
carbonic  acid. 

It  is  often  stated  that  hydrogen  is  a  gas  of  greater  heating 
power  than  carbonic  oxide,  but  as  a  matter  of  fact  for  gas  engine 
purposes  this  is  not  so  ;  hydrogen,  it  is  true,  weight  for  weight 
evolves  far  more  heat  by  its  combustion  than  any  other  substance, 


The  Production  of  Gas  for  Motive  Power  365 

but  volume  for  volume  carbonic  oxide  evolves  rather  more  heat 
than  hydrogen.  Hydrogen  evolves  by  the  combustion  of  i  Ib. 
weight  34170  heat  units,  or  enough  heat  to  raise  34170  Ibs.  of 
water  through  i°  C,  but  this  figure  includes  the  heat  evolved  on 
liquefying  the  steam,  formed  by  the  combustion,  in  the  calorimeter, 
which  at  637  heat  units  per  Ib.  of  water  gives  9x637  =  5733 
heat  units  absorbed  in  forming  steam  produced  by  burning  i  Ib. 
of  hydrogen.  So  that  from  34170  heat  units  must  be  deducted 
5733,  that  is  34170-5733  =  28437. 

This  number  28437  is  the  available  heat  produced  by  the 
combustion  of  hydrogen  for  the  purpose  of  a  gas  engine.  Now, 
unit  weight  of  carbonic  oxide  evolves  2400  heat  units,  and  unit 
volume  weighs  14  times  that  of  unit  volume  of  hydrogen,  so  that 
to  get  the  relative  heating  effects  of  equal  volumes  of  carbonic  oxide 
and  hydrogen  this  difference  in  weight  must  be  allowed  for. 
The  heat  evolved  by  unit  volume  of  CO  is  therefore  2400  x  14= 
33600;  that  is,  volume  for  volume  carbonic  oxide  evolves  ri8 
times  the  heat  of  hydrogen.  Hydrogen  and  carbonic  oxide  may 
therefore  be  taken  on  an  analysis  of  gases  by  volume  to  be  nearly 
equal  in  gas  engine  value.  The  percentage  of  total  combustible 
material  may  be  taken  roughly  as  representing  the  relative  heat- 
ing value  of  two  gases  :  from  this  it  appears  that  the  French  analy- 
sis of  Dowson  gas,  notwithstanding  the  high  percentage  of  CO2, 
represents  the  better  gas  of  the  two,  as  the  English  sample  has 
44-4  per  cent,  combustible  and  the  French  sample  4  5 '9  per  cent. 
The  French  author  gives  the  efficiency  of  the  producer  as  75  per 
cent. ;  that  is,  the  gas  will  give  75  per  cent,  on  combustion  of  the 
total  heat  which  the  original  fuel  would  have  given.  If  it  were 
certain  that  the  analysis  represented  the  composition  of  the  gas  as 
it  left  the  producer,  then  the  efficiency  could  be  calculated  from  the 
analysis  itself ;  but  as  the  gases  pass  through  scrubbers  and  coolers 
before  reaching  the  gas  holder,  and  thereby  lose  carbonic  acid  and 
water  vapour,  it  is  impossible  to  calculate  the  efficiency  of  the 
producer  with  accuracy  from  the  analysis, 

Dowson  gas  of  the  composition  given  at  page  363  requires  for 
the  complete  combustion  of  i  cb.  ft.  as  nearly  as  possible  0*24 
cb.  ft.  of  oxygen  or  1-13  cb.  ft.  of  atmospheric  air;  that  is, 
Dowson  gas  requires  for  its  combustion  a  little  more  than  its  own 


366  The  Gas  Engine 

volume  of  air.  From  Table  III.  in  Appendix  II.  it  will  be  seen 
that  in  samples  of  illuminating  coal  gas  from  twenty  different  gas 
works  in  Britain  the  proportion  of  air  required  for  complete 
combustion  varied  from  5-19  vols.  to  7^40  vols.  of  air;  that  is, 
i  cb.  ft.  of  coal  gas  required  in  one  town  only  5-19  cb.  ft.  of  air 
for  its  combustion,  while  i  cb.  ft.  of  the  gas  of  another  town 
required  7*40  cb.  ft.  of  air. 

The  heat  evolved  by  i  cb.  ft.  of  Dowson  gas  is  about  one- 
fourth  of  that  evolved  by  an  average  gas,  such  as  Birmingham  gas, 
so  that  the  amount  required  in  a  gas  engine  cylinder  is  about 
four  times  what  would  have  been  required  with  coal  gas.  For  a 
gas  admitted  to  the  cylinder  in  the  proportion  of  i  of  coal  gas  to 
8  of  mixture  of  gas  and  air,  it  would  require  4  of  Dowson  gas,  but 
this  would  leave  too  little  air  for  combustion.  Consequently  till 
very  recently  the  diagram  obtained  in  a  gas  engine  cylinder  from 
Dowson  gas  did  not  give  so  high  an  average  pressure  as  coal  gas. 
In  ordinary  practice,  according  to  the  author's  experience,  it  was 
not  safe  to  rely  on  an  average  available  pressure  of  more  than 
50  Ibs.  per  sq.  in.,  while  coal  gas  easily  gave  70  Ibs.  By  using, 
however,  Messrs.  Crossley  and  Atkinson's  new  scavenging  engine, 
enough  air  can  be  introduced  to  burn  a  larger  quantity  of  Dowson 
gas,  so  that  now  an  average  available  pressure  of  65  Ibs.  per 
sq.  in.  can  be  relied  upon  in  such  an  engine  using  Dowson  gas 
and  giving  about  40  I  HP  ;  in  larger  engines  higher  available 
pressures  may  be  obtained,  and  in  smaller  engines  lower 
pressures. 

To  secure  the  good  and  economical  working  of  a  gas  engine 
it  is  absolutely  necessary  that  the  gas  supplied  to  it  should  be  of 
fairly  uniform  quality,  otherwise  the  engine,  which  is  adjusted  to 
draw  in  gas  and  air  in  a  fixed  proportion,  may  at  one  moment 
be  taking  in  a  gas  of  such  richness  that  the  air  allowed  is  in- 
sufficient for  combustion,  and  at  another  time  the  gas  may  be  so 
poor  that  the  air  is  too  largely  in  excess,  and  so  a  weak  explosion 
or  no  explosion  at  all  is  obtained. 

One  of  the  advantages  of  a  fixed  carbon  fuel,  such  as  anthracite 
or  coke,  with  little  or  no  volatile  matter,  is  that  when  such  fuel  is 
added  to  the  generator  no  gases  are  given  off  by  destructive 
distillation.  In  the  Dowson  generator,  fig.  171,  if  such  gases  were 


The  Production  of  Gas  for  Motive  Power          367 

given  off  at  each  charging  with  fuel,  then  they  would  find  their  way 
direct  into  the  gasometer  and  practically  fill  the  gasometer  with 
gases  such  as  CH4,  C2H4  and  pure  H  to  such  an  extent  as  to 
render  the  gas  much  too  rich  to  be  burned  in  the  gas  engine 
cylinder  with  the  proportion  of  air  allowed  for  the  ordinary 
Dowson  gas.  The  addition  of  anthracite  or  coke  produces  no 
such  disturbance  ;  further  the  composition  of  the  incandescent 
charge  in  the  generator  remains  fairly  constant  until  it  is  wholly 
consumed,  so  that  there  is  no  variation  from  that  cause.  Again,  if 
ordinary  flaming  coal  be  added  to  the  producer,  large  quantities 
of  condensible  carbon  compounds,  such  as  tar,  would  be  given  off, 
and  the  scrubbing  and  purifying  would  be  much  more  difficult. 
Altogether  the  Dowson  apparatus,  although  it  solves  the  problem 
in  an  easy  and  practical  manner,  limiting  its  fuel  to  anthracite  and 
coke,  does  not  do  so  for  the  cheaper  but  more  troublesome  fuels 
used  under  the  ordinary  steam  boiler.  The  percentage  of  heat 
obtained,  however,  from  the  gas  generated,  75  per  cent,  of  the 
original  heat  of  the  fuel,  compares  satisfactorily  with  the 
efficiency  of  an  ordinary  Lancashire  steam  boiler  without 
economisers. 

Lencauchez  Gas  Producer. — The  Lencauchez  producer  is  not 
to  the  author's  knowledge  in  use  in  England,  but  it  is  reported 
favourably  upon  by  Professor  A.  Witz  and  others  in  France.  It 
is  an  attempt  to  improve  upon  Dowson's  producer  in  such  manner 
as  to  save  some  of  the  heat  at  present  lost  with  the  highly  heated 
gases  leaving  the  producer,  to  get  back  in  fact  some  of  the  heat 
which  at  present  is  entirely  lost  by  cooling  the  gas  ;  and  further 
to  make  such  producers  suitable  for  use  with  fuel,  such  as 
slack  or  other  fuel  giving  off  considerable  quantities  of  volatile 
carbon. 

Fig.  174  is  a  vertical  side  section,  and  fig.  175  is  a  front 
elevation  part  in  section  of  this  producer.  A  is  the  gas  generator 
lined  with  fire  brick,  B  is  the  grate  and  c  the  closed  ash  pit,  D  is 
the  feed  hopper  with  upper  and  lower  door  or  valves,  E  is  a  bridge 
passing  down  from  above  and  causing  the  gas  to  flow  from  about 
the  middle  of  the  producer  instead  of  from  the  top,  F  is  the  gas 
discharge  passage,  which  first  passes  up  through  the  brickwork  and 
then  passes  up  a  flue  or  tube  formed  through  two  cylindrical 


368 


The  Gas  Engine 


FIG.  175. 


FIG.  174. — Lencauchez  Gas  Producer  (vertical  side  section). 
FIG.  175. — Lencauchez  Gas  Producer  (front  elevation,  part  section). 


The  Production  of  Gas  for  Motive  Power  369 

vessels  or  chambers  respectively  G  and  H.  The  lower  vessel  G  is 
an  air  and  steam  heater,  the  upper  is  a  boiler.  From  the  upper 
vessel  the  gas  passes  to  the  gas  holder  by  the  pipe  i  ;  K  is  a  valve 
at  the  top  of  the  branch  to  allow  the  gas  to  be  ignited  and  sampled 
at  any  time  either  at  starting  or  during  operation.  The  action  is 
as  follows  :  The  generator  is  started  much  in  the  same  way  as 
has  been  described  for  Dowson,  but  the  hot  gases  ascending  the 
tube  or  passage  F  heat  the  vessels  G  and  H,  steam  is  formed  in  H, 
but  without  pressure,  and  it  flows  into  the  casing  G  by  way  of  the 
pipe  H1 :  air  is  forced  into  the  casing  G  from  the  pipe  L  by  means 
of  a  fan  or  other  positive  blower,  it  mixes  with  the  steam  proceed- 
ing from  the  upper  vessel  and  both  are  considerably  heated,  the 
air  then  flows  by  the  pipe  M  shown  in  dotted  lines  to  the  closed 
ash  pit  c.  The  heated  mixture  of  air  and  steam  passes  through 
the  incandescent  fuel  in  the  generator,  forms  carbonic  oxide  and 
hydrogen  and  passes  up  the  passage  F.  The  fuel  meantime  which 
is  in  the  upper  part  of  the  generator  A  is  by  the  heat  from  below 
being  subjected  to  destructive  distillation,  and  the  gases  formed, 
as  they  cannot  escape  by  the  hopper,  pass  down  through  the 
incandescent  fuel  and  then  escape  by  the  passage  F  with  the  other 
gases.  This  descent  through  the  incandescent  fuel  is  stated  to 
have  the  effect  of  splitting  up  all  the  tarry  matters  contained  in 
the  volatile  gases  and  fixing  the  gases  in  permanent  form  as  CH4, 
C2H4  and  H.  The  fuel  does  not  reach  the  incandescent  part 
until  it  is  thoroughly  coked.  By  this  arrangement  of  separating 
the  freshly  charged  fuel  from  the  incandescent  fuel  and  passing 
the  hot  gases  away  from  a  part  of  the  generator  which  contains 
nothing  but  incandescent  fuel,  it  is  stated  that  the  difficulty  of 
using  fuels  such  as  common  slack  is  avoided. 

The  producer  is  ingenious  and  worthy  of  careful  study,  but 
the  author  is  of  opinion  that  with  such  fuel  it  will  be  found  that 
the  system  of  destroying  the  tar  and  coking  the  fresh  fuel  is  not 
sufficiently  perfect,  and  that  dirtier  gas  of  irregular  composition 
will  be  fed  to  the  engine.  With  anthracite  or  coke,  however,  the 
Lencauchez  producer  will  work  well  and  give  some  economy  over 
the  Dowson. 

According  to  Richards  this  producer  with  French  anthracite 
gives  gas  of  the  following  composition  : 

B  B 


TTNTVF.RSTTV 


37O  The  Gas  Engine 

ANALYSIS  OF  LENCAUCHEZ  GAS  (ANTHRACITE). 

Nitrogen,  N 47 '84 

Carbonic  oxide,  CO        .         .         ,27-32^ 

Hydrogen,  H          ....  i8'34  !_48.46  combustible. 

Olefiant  gas,  CH4  .         .         .         .  i'25 

Hydrocarbons,  C4H4      .         .         .  i'55' 

Carbonic  acid,  CO3         .         .         .  3'6o 

Sulphur  dioxide,  SO%      .         •         .  ©'04 

Sulphuretted  hydrogen,  HoS           .  o'o6 


According  to  Richards  the  loss  due  to  gasefying  is  only  13  per 
cent.  ;  if  this  be  true,  then  the  efficiency  of  the  producer  is  87  per 
cent.,  a  higher  efficiency  than  any  standard  test  of  a  steam  boiler. 
The  gas  is  considerably  better  than  the  best  analysis  shows  Dowson 
gas  to  be  ;  but  the  author,  although  he  can  understand  some 
advance  in  Dowson  practice,  cannot  see  that  so  much  can  be 
gained  by  the  apparatus  illustrated  as  to  increase  the  efficiency 
from  75  percent,  to  87  per  cent.  However,  Lencauchez' apparatus 
is  a  step  in  the  right  direction  and  is  worthy  of  careful  consideration. 

The  tar  difficulty  in  gas  producers  for  gas  engines  is  a  very 
serious  one,  and  even  with  Dowson's  apparatus  more  tarry  matter 
reaches  the  engine  than  when  town  gas  is  used.  This  neces- 
sitates frequently  cleaning  the  valves.  A  very  little  tar  getting  to 
the  valves  soon  makes  them  work  with  difficulty,  and  so  deranges 
the  whole  action  of  the  engine. 

Other  Gas  Producers. — Several  gas  engine  makers  now  manu- 
facture gas  producers  themselves,  notably  Messrs.  Tangyes  Lim. 
and  Messrs.  Dick,  Kerr  &  Co.  Lim.,  but  the  general  principles 
involved  are  those  common  to  the  Dowson  and  Lencauchez 
producers,  so  that  at  present  till  more  experience  has  been  gained 
it  is  needless  to  discuss  their  points  of  departure.  Many  gas  pro- 
ducers which  are  used  for  ordinary  furnace  work  such  as  Siemens' 
and  Wilson's,  are  not  applicable  to  gas  engine  work  because  of  the 
tarry  nature  of  the  gas  given  off  and  the  comparative  irregularity 
of  its  composition. 

Water  gas,  too,  is  sometimes  stated  as  useful  for  gas  engines, 
but  from  an  examination  of  tests  with  water  gas  plant  it  appears 
that  although  the  gas  obtained  is  much  richer  in  combustible 
material,  the  loss  in  making  it  is  greater  than  that  with  producer 


The  Production  of  Gas  for  Motive  Power          371 

gas.  Water  gas  is  produced  by  blowing  steam  upon  white  hot 
coke,  when  the  steam  is  split  up,  as  described,  into  carbonic  oxide 
and  oxygen  ;  after  a  short  time  the  carbon  loses  heat,  and  air  is 
blown  in  to  heat  it  up  again.  The  gases  leaving  the  generator  in 
this  blowing-up  process  give  up  their  heat  as  they  leave  by  passing 
through  a  regenerator,  which  regenerator  is  used  to  heat  up  the 
entering  steam  and  air  on  the  next  process.  In  this  way  gas  is 
obtained  with  but  little  nitrogen. 

Water  gas  is  extensively  made  in  America  for  town  supply,  and 
in  this  country  also  it  is  now  considerably  manufactured  by  the  gas 
companies  to  mix  with  ordinary  coal  gas. 

The  water  gas,  however,  although  it  works  a  gas  engine  quite 
well,  and  many  gas  engines  in  America  do  use  it,  is  not  interesting 
from  the  point  of  view  of  competing  with  the  steam  boiler. 

Fuel  Consumption  of  Gas  Engines  with  Producer  Gas. — 
Mr.  Dowson  made  a  test  with  a  Crossley  Otto  engine  of  60  HP 
nominal,  using  his  producer  gas,  for  which  he  claims  the  very 
low  fuel  consumption  of  0^762  Ib.  of  anthracite  and  coke 
during  a  working  test  of  eight  hours.  Allowing  for  the  total  loss 
of  fuel  in  the  generator  standing  all  night  and  also  clinkering,  the 
consumption  is  only  brought  up  to  0*873  Ik.  Per  IHP  hour. 

The  engine  was  of  the  well-known  Crossley  Otto  two-cylinder 
type.  The  leading  particulars  of  the  trial  are  as  follows  : 

Nominal  power  of  engine      .         .         .         .         60  HP 

Diameter  of  cylinders 17  ins. 

Length  of  stroke 24     ,, 

Duration  of  trial 8  hrs.  (9.40  A.M.  to  5.40  P. M  ). 

Total  revolutions  of  crank  shaft  during  trial .         .     74751  =  15573    Per  minute. 
,,      explosions  in  left  cylinder    ....     25908=   53 '975 
,,   right  cylinder          .         .         .     26619=   55'456 

(79 -9  left    cylinder. 
Mean  available  pressure  on  indicator  diagrams     .   |  "7-0  right 

78-9  average  of  both. 
j    59 '3  left     cylinder. 
Mean  indicated  horse  power  during  trial     .         .   \    en -4  right 

1187 

Mean  temperature  of  gas  in  bags  near  engine        .        .         .  67°  F. 

,,                     ,,           air  to  engine 5°°  F. 

,,                    ,,           water  overflow  from  left    cylinder       .  125°  F. 

right       ,,              .  119°  F. 

„                    ,,          feed  water  of  boiler                        »  75°  *'• 

n  B  2 


372  The  Gas  Engine 

Mean  pressure  of  gas  in  holder i£  in  water. 

,,             ,,         steam  in  boiler    .......  48  Ibs. 

Anthracite  l  consumed  in  generator  during  trial       ....  584  Ibs. 

Coke2                 ,,             ,,  boiler  to  get  up  steam  before  trial     .         .  30    ,, 

Coke  consumed  in  boiler  during  trial 14°    - . 

Anthracite  consumed  during  trial     .         .         .    0*615  lb.  per  IHP  working  hour. 
Coke  ,,  „          „      .        .        .    0-147       „ 

Total       .         .         .    0762       ,,  ,,  ,, 

Anthracite  put  in  generator  on  morning  after ') 

trial  to  make  up  for  loss  during  9  night  r  0*058       ,,  ,,  „ 

hours 56  Iks.  ' 

Anthracite   put    in    generator    on    following  ^ 

morning  after  raking  out  clinkers  &c.          i-o'o;3       ,,  •  ,,  ,, 

50  Ibs.  ) 


Total  loss  during  night  and  after  clinkering) 

106  Ibs.  J 


Total   consumption  of  anthracite    and   coke )      g 
during  trial  and  following  night   .         .      > 

Gas  consumed  5  at  rate  of  about  63  cubic  feet  per  IHP  per  hour. 
Anthracite  consumed  during  trial,  about  10  Ibs.  ,  Per  1,000  cubic  feet  of 

Anthracite  and  coke  consumed  during  trial,  about  12  Ibs.   J  gas  made. 

per  hour  =  50 -5  Ibs.  per  IHP  per  hour. 

Water  used  for  boiler    .         .       10         ,,  ,,       =   o'8         ,,  ,,  ,, 

Water  used  for  cleaning  gas       14         ,,  ,,       =    i'i         ,, 

Total  water  used  during  trial  624         ,,  ,,        —  S2  '4        »  »  " 

Total  water  used  for  gas-mak"  .  7^  gall°n"  per  *  >O?°  CUbiC 

I          feet  of  gas  made. 

Oil  used  for  cylinders  during  trial      .         .         ".  15  pint  at  2s.  gd.  per  gallon. 

.,         »      bearings       ,,         ,,         .         .         .         .  ii      ,,       is.  ^d.     ,,       ,, 

Coal  gas  5  used  for  heating  ignition  tubes          .         .  4^  cubic  feet  per  hour. 

{i  pair  stones  (4  feet  diameter)  24  elevators. 

13     ,,    rolls  (250  revolutions)  2  exhaust  fans. 

4     ,,    disks  (600  revolutions)  sundry  conveyors. 

14  ordinary  silks  pump. 

7  centrifugal  silks  shafting,  &c. 

4  purifiers. 

1  Anthracite  used  was  the  usual  kind  from  the  Gvvaun  Cae  Gurwen  Colliery 
Company,  Limited.  2  Coke  from  Gas  Light  and  Coke  Company. 

5  Rate  of  gas  consumed  was  measured  by  shutting  the  inlet  of  g-is  holder  and 
timing  the  fall  of  the  holder  through  6  feet,  while  the  engine  was  working. 

4  All  the  water  used  was  pumped  up  from  the  river  by  the  engine,  and  run  to 
waste.     Usually  the  water  used  for  cooling  an  engine  flows  to  and  from  an  over- 
head tank. 

5  Coal  gas  was  used  for  this  purpose,  because  Dowson  gas  could  not  be  taken 
from  the  main  supplying  the  engine,  and  there  was  no  .separate  outlet  from  the 
gas  holder. 


The  Production  of  Gas  for  Motive  Power  373 

This  is  a  valuable  test  as  showing  the  best  consumptions  of  fuel 
to  be  obtained  with  Dowson  gas  in  an  engine  giving  off  about 
120  HP  indicated,  but  it  is  of  course  lower  than  would  be 
obtained  in  ordinary  work  with  the  plant  handled  by  the  ordinary 
engineer. 

It  is  to  be  noted  also  that  the  level  of  fuel  in  the  generator  was 
estimated  as  the  same  at  the  end  as  at  the  beginning  of  the  eight  hours' 
test.  The  author  considers  it  rather  dangerous  to  estimate  the  fuel 
remaining  in  this  way  ;  great  errors  might  easily  creep  in  by  this 
practice.  The  only  accurate  method  is  to  empty  the  generator  at 
the  start  and  weigh  out  all  the  fuel  for  filling  up  and  starting,  then 
to  rake  out  the  fuel  remaining  and  damp  it  out  and  weigh  at  the 
end  of  the  test. 

In  1890,  Prof.  A.  Witz  tested  a  Simplex  gas  engine  of  100 
HP  at  the  Paris  Exhibition,  and  found  with  Dowson  gas  a  fuel 
consumption  of  1*34  Ib.  of  English  anthracite  per  brake  HP  hour. 

A  recent  test  of  an  Otto  engine  of  TOO  HP  with  two  cylinders 
was  made  at  Philadelphia  by  Mr.  H.  W.  Spangler,  using  producer 
gas  made  in  a  producer  somewhat  similar  to  the  Lencauchez  under 
Taylor's  American  patent.  The  efficiency  of  the  producer  was 
found  to  be  69-1  per  cent.  ;  that  is,  the  gas  produced  by  it  would 
produce  on  combustion  69-1  per  cent,  of  the  heat  which  could  be 
got  by  burning  the  original  fuel  put  into  it.  The  engine  indicated 
130  horse  and  consumed  1-315  Ib.  of  coal  per  IHP  hour.  The 
coal  used  in  the  producer  gave  the  following  analysis  : 

ANALYSIS  OF  COAL  USED  IN  SPANGLER'S  TEST. 

Moisture 4'2O 

Volatile  and  combustible  carbon  and  hydrogen       .         .  6 '88 

Fixed  carbon 80*41 

Ash  8-51 

Sulphur 074 

10074 

This  coal  is  evidently  inferior  to  English  anthracite,  so  that 
the  result  of  1-31  Ib.  per  IHP  is  very  fair.  Allowing  for  ash 
and  moisture,  the  combustible  matter  burned  was  only  0*830  Ib. 
per  IHP  hour. 

The  author  tested  an  Otto  engine  recently  with  Dowson  gas, 
and  found  in  a  seven  and  a  half  hours'  test  a  consumption  of 


374 


The  Gas  Engine 


1-87  Ib.  of  anthracite  and  coke  per  IHP.  The  engine  indicated 
23-5  horse  power  at  210  revolutions.  Fig.  176  is  a  diagram 
from  the  engine  on  that  occasion,  with  the  leading  particulars 
marked  under  it. 

In  this  case,  however,  the  author  considers  that  better  results 
would  have  been  obtained  if  the  producer  had  supplied  two  engines 
instead  of  one ;  the  consumption  of  anthracite  in  the  generator, 


00 


Nominal  HP,  14  ;  diam.  of  cy'inder,  IT'S"  ;  length  of  stroke,  21}"  ;  revs,  per 
Ib.    (anthracite  and  coke);  indicated  HP, 


210;   fuel  per   IHP   hour, 

BHP,    27  '5  ;    mean   pressure,    58  '4   Ibs.    per   sq. 

pressure  ot  compression,  83  Ibs.  above  atmosphere. 


pressure,    200  Ibs. 


FIG.  176.  —  Crossley  Otto  Scavenging  Engine  (diagram  with  Dowson  gas). 

about  half  a  hundredweight  per  hour,  was  too  little  for  maximum 
efficiency. 

From  these  tests,  then,  it  may  be  considered  as  absolutely 
established  that  in  ordinary  work  the  consumption  of  anthracite 
in  a  good  Otto  engine  using  Dowson  or  a  similar  gas  ranges  from 
i|  Ib.  per  IHP  for  an  engine  of  about  30  IHP  to  i  Ib.  for  an 
engine  of  130  IHP. 


375 


CHAPTER   IV. 

THE    PRESENT    POSITION    OF    GAS    ENGINE    ECONOMY. 

IN  this  chapter  the  author  will  discuss  the  fuel  consumption  of  the 
gas  engine  at  present  and  the  economy  obtained  since  1886  ;  he 
will  examine  the  various  causes  of  the  advance  with  the  object 
of  understanding  the  direction  of  progress,  and  if  possible  of 
indicating  the  lines  still. open  for  improvement. 

The  Crossley  Otto  engine  has  made  wonderful  progress  in 
reducing  gas  consumption  since  1886,  but  for  the  purpose  of  com- 
parison it  is  desirable  to  go  back  to  1882  ;  at  the  latter  date  the 
Crossley  engine  gave  an  indicated  horse  power  hour  on  23*7  cb.  ft. 
of  London  gas  of  such  heating  power  that  the  indicated  efficiency 
of  the  engine  is  E=cri7,  that  is  o'iy  of  the  whole  heat  supplied 
to  the  engine  appears  on  the  diagram  as  indicated  work. 

In  1888  the  engine  submitted  by  Messrs.  Crossley  for  the 
Society  of  Arts  trials  consumed  20-55  cb.  ft.  per  IHP  hour  of 
London  gas  of  a  heating  value  of  483270  ft.  Ibs.  per  cb.  ft.  Cal- 
culating from  this  and  reducing  the  gas  measurements  for  tempera- 
ture and  pressure,  the  indicated  efficiency  becomes  0-21.  At  the 
end  of  the  year  1888  it  may  be  taken  that  the  best  result  obtain- 
able from  an  Otto  engine  of  about  17  IHP  was  a  conversion  of  0*2 1 
of  the  heat  given  to  it  into  indicated  work. 

The  third  test  taken  for  comparison  was  made  by  the  author 
at  Messrs.  Crossley's  works,  Openshaw,  on  August  31,  1894,  on 
an  engine  of  7  in.  diameter  cylinder  and  15  in.  stroke.  This 
engine  developed  at  200  revs,  the  great  power  of  12  brake  horse 
and  indicated  14  horse  or  a  consumption  of  14-5  cb.  ft.  of  Open- 
shaw gas  per  IHP  hour  and  17  cb.  ft.  per  BHP  hour. 

Taking  the  heating  valueof  Openshawgas  as  530000  foot  pounds 
per  cb.  ft.  at  17°  C  and  147  Ibs.  pressure,  the  indicated  efficiency 


376  The  Gas  Engine 

is  0-25  ;  that  is,  the  engine  converts  0*25  of  all  the  heat  given  to  it 
into  indicated  work.  This  is  an  extraordinarily  good  result,  much 
lower,  in  fact,  than  any  result  ever  obtained  before  to  the  author's 
knowledge.  To  make  certain  that  there  was  no  mistake,  the  author 
had  the  gas  meter  tested  and  the  brake  weights  and  measurements 
all  carefully  checked  in  his  presence. 

The  Messrs.  Crossley  have,  therefore,  made  a  very  substantial 
improvement  in  the  economy  of  gas  since  1882,  and  it  is  interesting 
to  note  that  each  step  of  diminished  gas  consumption  is  attended 
by  an  increase  in  compression  ;  this  is  very  evident  from  the  table 
below. 

ABSOLUTE  INDICATED  EFFICIENCY  OF  CROSSLEY  OTTO  ENGINES 
OF  SIMILAR  SIZE  SINCE  1882. 

Efficient: v  Pressure  of  compression 

above  atmosphere 

(1)  1882-88 0-17  .         .         38  Ibs.  per  sq.  in. 

(2)  1888-94 0-21.         .         66 "6  Ibs.    ,,     ,, 

(3)  l894 0-25.         .         87-5  Ibs.    ,,     „ 

The  experiments  giving  efficiencies  under  (i)  and  (2)  were 
made  with  engines  of  9  in.  diameter  cylinder  and  9^  in.  diameter 
cylinder  respectively,  both  engines  having  18  in.  stroke,  so  that  the 
engines  may  be  considered  to  be  of  the  same  dimensions  so  far  as 
change  of  economy  due  to  change  of  dimensions  is  concerned.  The 
result  (3),  on  the  contrary,  was  obtained  with  an  engine  of  7  in. 
diameter  cylinder  and  15  in.  stroke,  so  that  0^26  would  more  pro- 
perly represent  the  efficiency  to  be  obtained  from  an  engine  of 
the  same  dimensions  as  in  the  other  experiments. 

From  these  numbers  it  is  evident  that  economy  increases  with 
increased  compression,  but  now  the  question  arises  :  Does  the 
increased  compression  completely  account  for  the  improved  per- 
formance ?  If  the  calculated  result  from  the  various  compression 
pressures  accounts  for  the  whole  change  of  gas  consumption 
accompanying  change  of  pressure,  then  it  is  evident  that  to  the 
increase  of  compression  is  to  be  credited  the  improved  economy. 

To  test  this  the  author  has  calculated  by  formula  10  on  p.  53 
the  theoretical  efficiency  of  an  air  engine  in  which  no  practical 
losses  occurred,  the  air  engine  having  the  same  proportion  of  com- 
pression space  as  the  actual  gas  engines.  Those  theoretical 
efficiencies  are  shown  in  the  table  below  placed  beside  the  actual 


The  Present  Position  of  Gas  Engine  Economy       377 

efficiencies  obtained  in  the  gas  engine  ;  a  column  is  also  given 
showing  the  ratio  between  the  ideal  and  actual  efficiencies,  and 
other  columns  showing  the  dimensions  of  the  engines,  the  gas  con- 
sumption per  IHP  hour,  the  ratio  of  compression  space  to  volume 
swept  by  piston,  and  the  pressure  of  compression  in  pounds  per 
square  inch  above  atmosphere. 

THEORETIC  INDICATED  EFFICIENCY  OF  CROSSLEY  OTTO  ENGINES  WITH 

DIFFERENT     COMPRESSIONS     COMP  \RED     WITH     ACTUAL     INDICATED 

EFFICIENCIES  WITH  THE  SAME  COMPRESSIONS. 


E  =  calculated 
efficiency  for  perfect 
Otto  cycle  engines 
from  compression 
space  volume 

E  =  actual  indicated 
efficiency  from 
diagrams  and  gas 
consumption 

Ratio  of 
actual  to 
ideal 
efficiency 

nder  diameter 

inder  stroke 

of  compression 
to  space  swept 
by  piston 

ire  of  compres- 
above  atmos. 

consumption 
-IHPhour 

o  v 

U 

U 

n 

^'33 

£ft 

ins. 

ins. 

Ibs. 

cb.  ft. 

00     o-33 

0-17 

'33 

9-0     18 

0-6 

38 

24 

(2)     0-40 

0'2I 

•40 

9  '5 

18 

0-4 

6i'6 

2(5-5 

(3)     0-428 

0-25 

•428  ~°58 

7-0 

J5 

c-34 

87-5 

14-8 

From  this  table  it  is  evident  that  the  improved  economy  is 
fully  accounted  for  by  the  increased  compression  ;  in  every  case 
the  actual  indicated  efficiency  obtained  from  the  various  gas 
engines  is  a  little  more  than  half  of  that  which  would  be  given  by 
an  ideal  air  engine  following  the  same  cycle  in  a  perfect  manner 
without  loss  of  heat  to  the  sides  of  the  cylinder. 

It  is  interesting  to  observe  that  the  actual  efficiency  improves 
somewhat  more  rapidly  with  the  increase  of  compression  than 
does  the  thermodynamic  advantage  due  to  compression  ;  that 
is,  when  the  theoretical  efficiency  is  0*33  the  actual  experimental 
efficiency  is  -33  x  -51  =  '17  :  with  theory  0-40  the  actual  efficiency 
is  -40  x -53=0-21,  while  with  0-428  theory  the  actual  is  0-428  x 
•58=-25. 

The  proportion  of  the  theoretical  efficiency  actually  obtained 
in  practice  thus  rises  from  0*51  to  0-58.  This  means  that  with 
higher  compressions  in  addition  to  the  thermodynamic  advantage 


378 


The  Gas  Engine 


due  to  change  of  cycle  there  is  also  a  further  advantage  due 
to  a  diminution  of  proportional  loss  of  heat  to  the  cylinder 
walls. 

From  this  it  follows  that  very  probably  great  further  economies 
are  to  be  obtained  by  further  increase  of  compression,  care  being 
taken  of  course  to  preserve  a  properly  shaped  compression  space, 
that  is  a  space  having  small  cooling  surfaces  in  proportion  to  the 
volume  of  the  compressed  charge.  Some  of  the  advantage  is 
also  due  to  the  more  rapid  conversion  of  the  heat  of  the  explosion 
into  mechanical  work  by  reason  of  the  small  space  through  which 


FIG.  177. — Comparative  Diagram. 
Crossley  Otto  Engines  with  different  compressions. 

the  piston  moves  while  doing  a  large  part  of  the  total  work  of  its 
stroke. 

To  render  the  effect  of  compression  readily  visible  to  the  eye 
the  author  has  drawn  a  diagram,  fig.  177,  in  which  the  length  of 
the  line  a  b  represents  the  total  capacity  of  the  cylinder  including 
the  compression  space  ;  c  b  represent  the  stroke  and  a  c  the  com- 
pression space  according  to  a  diagram  of  a  test  taken  by  the 
author  in  1888,  and  def  b  is  that  diagram  plotted  down  on  the 
scale  of  TJL^  inch  equal  to  one  pound. 

The  line  ag  represents  the  compression  space  and  gb  the 
stroke  of  the  Otto  engine  tested  by  the  Society  of  Arts,  while  h  i 


The  Present  Position  of  Gas  Engine  Economy      379 

k  b  is  the  diagram  taken  from  the  Society  of  Arts  Report  of  1888 
plotted  down  to  the  same  scale  as  the  first  diagram. 

The  line  a  I  represents  the  compression  space  and  /  b  the 
stroke  of  the  engine  tested  by  the  author  at  Messrs.  Crossley's 
works,  while  m  n  o  b  is  the  diagram  fig.  135,  p.  316,  also  plotted 
to  y^  in  scale. 

The  three  diagrams  are  also  numbered  i,  2,  and  3.  It  is  quite 
evident  that  No.  2  is  larger  in  area  than  i,  and  that  3  is  consider- 
able larger  than  both.  These  diagrams  show  in  a  clear  way  the 
great  advance  made  by  increasing  compression  on  the  indicator 
diagram.  Mr.  Atkinson  considers  the  improved  results  obtained 
with  the  Crossley  Atkinson  scavenging  engine  to  be  due  not  to 
any  increase  in  compression,  but  to  the  displacement  of  the 
burned  gases  from  the  cylinder,  and  he  does  not  consider  that 
increased  compression  has  anything  to  do  with  the  increased 
economy.  These  opinions  he  advanced  in  a  paper  read  before 
the  Manchester  Association  of  Engineers. 

The  author  has  always  advocated  and  believed  in  scavenging 
a  cylinder  by  means  of  air,  and  in  many  of  his  engines  he  has 
entirely  discharged  the  exhaust  gases  by  air  forced  in  by  a  pump. 
He  has  never  been  able,  however,  to  credit  such  scavenging  with 
more  than  5  per  cent,  economy  as  compared  with  the  same  engine 
working  at  the  same  compression  and  retaining  the  exhaust  gases. 

The  results  of  many  tests  with  gas  engines  of  the  three  cycle 
variety  of  the  Otto  type,  in  which  one  revolution  is  devoted  to 
replacing  the  whole  of  the  exhaust  gases  by  air,  proves  to  demon- 
stration that  the  gas  consumption  per  IHP  is  not  materially 
reduced  by  the  act  of  displacing  the  exhaust  products.  Such 
engines  have  been  constructed  by  Linford,  Griffin,  Barker  and 
others  before  the  expiry  of  the  Otto  master  patent,  and  although 
in  them  the  exhaust  products  were  entirely  displaced  by  air 
they  did  not  show  a  marked  economy. 

The  matter,  however,  may  be  considered  as  positively  deter- 
mined by  the  experiments  communicated  to  the  author  by  Mr.  A. 
R.  Bellamy,  and  the  diagrams  given  at  figs.  139  and  140  showing 
with  a  compression  of  60  Ibs.  per  sq.  in.  above  atmosphere 
a  consumption  of  19  cb.  ft.  per  IHP  hour,  and  with  a  com- 
pression of  90  Ibs.  a  consumption  of  17*6  cb.  ft.  per  IHP.  In 


380  The  Gas  Engine 

comparing  these  figures  with  the  results  obtained  by  the  author  at 
Messrs.  Crossley's  works,  it  is  to  be  remembered  that  Openshaw 
gas  is  considerably  greater  in  heating  value  than  the  gas  used  by 
Messrs.  Andrew  cSz:  Co.  at  Reddish.  Mr.  Bellamy's  diagrams  were 
taken  from  the  same  engine  with  two  different  compression 
chambers  successively  applied. 

Scavenging  by  pure  air  has,  however,  great  practical  advantages. 
The  average  available  pressure  which  can  be  economically  obtained 
in  the  cylinder  is  greatly  increased,  and  for  really  large  engines  it 
is  absolutely  necessary  to  scavenge  in  order  to  avoid  premature 
explosions.  This  is  especially  true  when  high  pressures  of  com- 
pression are  adopted.  With  such  compressions  premature  ex- 
plosions are  caused  by  the  presence  of  the  hot  burned  gases, 
and  when  these  hot  gases  are  removed  by  pure  air  the  cold  pure 
mixture  may  be  compressed  to  very  high  pressures  without  danger 
of  early  ignition.  The  admission  of  air  in  the  first  place  also 
prevents  any  chance  of  igniting  the  incoming  charge  during  the 
charging  stroke. 

The  author  therefore  considers  that  Messrs.  Crossley  & 
Atkinson's  new  scavenging  device  is  a  most  valuable  invention, 
inasmuch  as  it  permits  of  clearing  out  all  waste  products  by  a 
device  so  simple  as  to  add  no  complications  to  the  engine.  It  is 
more  valuable,  however,  for  large  engines  than  for  small  ones,  as 
it  is  much  more  desirable  to  discharge  exhaust  products  in  large 
than  in  small  engines.  The  invention  is  especially  applicable  to 
engines  using  Dowson  gas,  and  it  considerably  increases  the 
available  pressure  with  such  engines,  by  so  increasing  the  air 
supply  present  as  to  enable  more  gas  to  be  burned  economically 
in  the  cylinder. 

Figs.  178,  179  are  diagrams  taken  from  the  same  'scavenging' 
engine  with  ordinary  gas  and  Dowson  gas. 

The  engine  has  a  1 7-inch  diameter  cylinder  and  24-inch  stroke. 
In  fig.  178,  the  coal  gas  diagram,  the  power  indicated  is   121 
horse,  with  an  average  available  pressure  of  ii3'5  Ibs.  per  sq.  in. 
In  fig.  179,  the  Dowson  gas  diagram,  the  very  satisfactory  avail- 
able pressure  of  97-4  Ibs.  is  obtained. 

The  engine  is  rated  at  30  HP  nominal. 

The  Dowson  diagram  is  a  great  improvement  on  that  obtained 


The  Present  Position  of  Gas  Engine  Economy       381 

with  the  same  gas  on  a  non-scavenging  engine  ;  the  highest 
available  pressure  claimed  by  Mr.  Dowson  for  an  engine  this  size 
is  82  Ibs.  per  sq.  in. 

Even  with  the  scavenging  device,  however,  it  does  not  seem 
safe  to  rely  upon  a  higher  pressure  for  anything  like  full  load 
than  65  Ibs.  persq.  in.  with  a  16  HP  nominal  Crossley  Otto. 

Methods  still  open  to  obtain  increased  Economy.  —  Modification 
may  still  be  made  in  the  indicator  diagram  of  the  gas  engine  to 
further  increase  efficiency,  and  the  author  will  now  discuss  such 
points  as  appear  to  him  capable  of  improvement.  In  doing  this 
the  author  will  refer  to  the  Otto  cycle,  but  it  is  to  be  remembered 
that  the  impulse-every-revolution  engines  may  be  arranged  to 
produce  any  of  the  results  brought  about  by  the  Otto  engine. 

The  author  has  pointed  out  that  the  actual  indicated  efficiency 
of  a  gas  engine  increases  with  the  theoretic  efficiency,  and  that 
the  actual  efficiency  varies  from  0-51  to  0*58  of  the  theory.  The 
actual  indicated  efficiency  also  increases  with  the  dimensions  of 
the  engine,  other  things  being  similar,  when  the  ratio  of  compres- 
sion space,  and  therefore  the  theoretical  efficiency,  remains 
constant.  Thus  at  p.  377  an  engine  of  9^  ins.  cylinder  and  18 
in.  stroke  having  a  theoretic  efficiency  of  0*40  gave  a  practical 
indicator  efficiency  of  0*21  or  0*53  of  the  theory. 

Referring  to  a  .careful  test,  already  mentioned,  of  a  100  HP 
double  cylinder  Otto  engine  made  in  Philadelphia  by  Mr. 
H.  W.  Spangler,  it  will  be  found  that  the  cylinders  were  each  14 
in.  diameter  by  25  in.  stroke  ;  the  engine  gave  as  an  average  127 
IHP  and  92*5  brake  HP  at  160  revolutions  per  minute.  The 
clearance  space  was  practically  28  per  cent,  of  the  whole  cylinder 
volume,  that  is  28  per  cent,  of  the  volume  swept  by  piston  + 
compression  space  volume. 

The  theoretic  efficiency  of  such  an  engine  is  0-41,  but  the 
actual  efficiency  was  found  to  be  0*277,  so  tnat 


0- 


The  actual  efficiency,  instead  of  being  only  0-58  of  the  theoretic, 
rises  to  '675  of  it,  due  to  change  in  the  dimensions  of  the  engine 
without  practical  change  in  the  compression. 

The  engine  mentioned  on  page  377  as   7  in.   diameter  and 


382 


The  Gas  Engine 


i<  in  stroke  gave  an  efficiency  of  0-25,  while  the  larger  engine 
of  ii  in.  diameter  cylinder  and  21  in.  stroke,  having  a  similar 
compression  space,  gave  an  efficiency  of  0-275. 


M.P.   113-5  LBS, 


FlG.  178. — Diagram,  Crossley  Otto  Engine  (coal  gas). 


60 


330 
300 
270 
240 
210 
1 80 
ISO 
20 

so 

60 
30  . 


FIG.  179. — Diagram,  Crossley  Otto  Engine  (Dowson  gas). 

The  theoretical   efficiency   in   both   cases  is  0-428,   and  the 
ratios  are : 

-^-=•58  and  '17  5  =  -643 
•428  -428 

The  actual  efficiency,  therefore,  increases  with  the  dimensions  of 
the  engine,  the  compression  remaining  constant. 


The  Present  Position  of  Gas  Engine  Economy       383 


COMPARISON  OF  THE  ACTUAL  AND  THEORETIC  EFFICIENCIES 
OF  OTTO  ENGINES  OF  DIFFERENT  DIMENSIONS. 


Engine  cylinder 

Relative 
capacity 

Theoretic 
efficiency 

Actual 
indicated 
efficiency 

Ratio  of  ac- 
tual and  ideal 
efficiency 

Nearly  equal]  7"  diam.  x  15"  stroke  . 

I 

•428 

•25 

-^=•58 

compression   i 
v  115    diam.  x  21    stroke 

377 

•428 

•275 

•428 

Nearly  equal  (9i"  diam-  x  l8"  stroke 

i 

•40 

•21 

•21 

compression  j 
(  14"  diam.  x  25"  stroke 

2-97 

•41 

•277 

•31-67 

41 

From  these  numbers  it  is  evident  that  efficiency  for  equal  com- 
pression increases  considerably  with  the  dimensions  of  the  engine. 

There  is,  however,  a  limit  to  this  increase  of  efficiency  with 
increased  dimensions. 

The  increase  in  the  efficiency  of  the  larger  engines  as  compared 
with  the  smaller  using  the  same  proportion  of  compression  space 
is  due  to  the  diminished  proportional  loss  of  heat  from  the  gases 
of  the  explosion  to  the  inclosing  metal  walls,  and  it  is  always  found 
that  in  larger  engines  the  expansion  curve  tends  more  and  more 
to  rise  above  the  adiabatic  line.  With  a  maximum  temperature 
of  explosion  of  about  1600°  C.  it  is  found  by  experiment  that 
the  actual  increase  of  temperature  due  to  explosion  accounts  for 
about  from  06  to  07  of  the  total  heat  of  the  gas  present ;  there 
is  therefore  heat  enough  present  in  a  gas  engine  of  ordinary 
proportions,  if  none  be  lost,  to  keep  up  the  temperature  during 
expansion  performing  work  to  the  maximum  1600°  during  the 
whole  expansion  stroke.  The  increase  in  dimension  if  carried 
to  an  extreme  could  therefore  only  reduce  the  loss  to  insignificant 
relative  proportions,  and  in  such  a  case  the  mass  of  incandescent 
gas  might  be  considered  to  lose  no  heat  whatever  to  the  walls  of 
the  cylinder. 

Assume  an  air  engine  in  such  a  case  ;  the  total  volume  of 
the  stroke  plus  clearance  space  being  i  cb.  ft. 

Assume  the  engine  to  have  a  compression  space  of  0*275  °f 
the  whole  cylinder  volume,  as  in  the  test  made  by  the  author  on 
Crossley's  Otto  scavenging  engine,  page  316.  Then  the  diagram 


The  Gas  Engine 


and  results  would  be  as  shown  in  fig.  180,  where  the  temperature 
of  explosion  is  1600°  C. 

From  this  it  will  be  seen  that  while  0-409  is  the  efficiency 
for  adiabatic  expansion,  then  0*346  is  the  efficiency  for  isothermal 
expansion  ;  from  this,  then,  it  appears  that,  allowing  for  the  known 
property  of  the  suppression  of  heat  in  a  gaseous  explosion,  the 


360 


300 


550 


200 


ISO 


100 
80 

eo 

4-0 

eon 


Efficiency  of  adiabatic  compression  and  expansion  =  0*409. 
Efficiency  01  adiabatic  compression  and  isothermal  expansion =o'346. 

FIG.  180. — Theoretical  Diagram, 
comparing  adiabatic  and  isothermal  expansion. 

utmost  efficiency  possible  for  an  engine  using  coal  gas,  having 
a  compression  space  of  0-275  °f  tne  total  cylinder  volume,  and 
expanding  to  the  same  volume  as  existed  before  compression, 
is  0-346,  so  that  the  efficiency  actually  attained  in  practice  is 

_2-I7.=o-8o  or  80  per  cent,  of  the  possible. 
'34° 

So  far,  then,  practice  has  shown  that  the  absolute  efficiency  of 
the  gas  engine  has  been  increased  from  17  per  cent,  in  1882  to 
practically  28  per  cent,  in  1895,  that  is  from  converting  17  percent, 
of  the  whole  heat  into  indicated  work  to  28  per  cent,  of  the  whole 


The  Present  Position  of  Gas  Engine  Economy       385 

heat,  and  this  great  change  in  economy  has  been  brought  about 
by  increase  in  compression  alone.  The  compression  pressure 
has  risen  from  35  Ibs.  per  sq.  in.  above  atmosphere  to  90  Ibs. 
per  sq.  in. 

The  question  now  arises,  How  far  can  this  compression  be  still 
enhanced?  It  will  be  observed  from  the  formula  10  on  page 
53  that  the  efficiency  increases  somewhat  slowly  at  the  higher 
pressures,  and  thus  a  limit  must  be  reached  beyond  which  the 
increasing  weight  and  dimensions  of  the  engine  parts  due  to  rising 
maximum  pressure  will  more  than  compensate  for  the  improved 
theoretical  economy. 

Assume,  for  example,  that  a  compression  of  210  Ibs.  per  sq.  in. 
above  atmosphere  is  feasible  ;  the  volume  of  the  compression 
space  will  then  be  0*144  of  the  total  cylinder  volume,  so  that  the 
theoretic  efficiency  of  such  an  engine  will  be 

/    i  \o-4o8 

E=i  — —  =  0-546 

\6'95/ 

The  ideal  efficiencies  for  different  compressions  thus  stand  : 

E  =  o'33    for  38  Ibs.  per  sq.  in.  compression  above  atmosphere. 
E  =  o'4O     ,,  66 '6     , ,  ,,  ,i  »  a 

E^o'546    ,,  210      ,,  ,,  ,,          -    ,, 

Such  a  compression  as  210  Ibs.  per  sq.  in.  above  atmosphere 
would  produce  with  an  explosion  temperature  of  1600°  C. 
a  maximum  pressure  of  675  Ibs.  per  sq.  in.  above  atmosphere, 
and  this  would  involve  an  engine  of  nearly  double  the  weight 
of  working  parts  as  compared  with  the  engine  tested  by  the 
author  at  Messrs.  Crossley's,  with  but  a  small  increase  in  power 
for  the  great  increase  in  weight. 

The  author  accordingly  considers  a  compression  of  200  Ibs. 
per  sq.  in.  as  considerably  above  the  limit  likely  to  be  useful 
in  a  simple  gas  engine  ;  to  render  such  compressions  possible 
he  considers  that  compound  engines  will  require  to  be  designed. 

The  gas  engine,  in  the  author's  opinion,  is  now  rapidly  nearing 
the  limit  of  advantageous  increased  compression,  so  that  no 
great  faither  economy  is  to  be  expected  there. 

Looking  at  diagram  3,  fig.  177,  however,  it  will  be  obsen  ed  that 

c  e 


386  The  Gas  Engine 

at  the  moment  of  opening  the  exhaust  valve  there  is  still  in  the 
cylinder  a  pressure  of  about  50  per  sq.  in.  above  atmosphere. 
It  is  obvious  that  if  the  cylinder  of  that  engine  had  been  longer 
and  the  piston  could  expand  farther,  the  pressure  could  have 
been  reduced  while  the  expanding  gases  were  performing  work  in 
it.  This  source  of  economy  has  long  been  obvious  to  engineers, 
and  many  have  attempted  to  realise  it  in  practice.  The  author 
has  calculated  an  ideal  case  of  this  kind  in  which  the  pressure  of 
compression  was  100  Ibs.  per  sq.  in.  above  atmosphere,  the 
explosion  temperature  1600°,  and  the  (adiabatic)  expansion  carried 
on  far  enough  for  the  contents  of  the  cylinder  to  fall  to  atmo- 
spheric pressure.  The  theoretic  efficiency  of  such  an  engine 
would  be  073,  and  with  an  engine  of  about  200  IHP  a  practical 
efficiency  of  073  x  -6= '438  is  probable. 

In  the  author's  opinion  efficiencies  of  45  per  cent,  of  the 
whole  heat  given  to  the  engine  are  now  within  the  reach  of  the 
engineer. 

The  question,  however,  as  to  whether  greater  or  less  expansion 
should  be  utilised  in  an  engine  is  altogether  a  matter  of  dimen- 
sions ;  for  small  engines  great  expansion  beyond  the  volume  of 
the  charge  before  compression  is  inadvisable,  as  the  reduction  of 
the  volume  of  mixture  dealt  with  at  each  stroke  may  readily  so  far 
increase  the  relative  loss  of  heat  to  the  cylinder  as  to  more  than 
neutralise  the  gain  obtained  from  the  extra  expansion. 

In  very  large  gas  engines,  it  will  be  undoubtedly  advisable 
to  adopt  the  compound  principle,  and  many  engineers  have 
attempted  compounding ;  so  far,  however,  compounding  is  not 
successful.  Otto,  Clerk,  Atkinson,  Crossley,  Burt,  Dick,  Kerr  £: 
Co.  and  others  have  attempted  compounding,  but  the  principles 
involved  are  not  yet  thoroughly  understood  and  require  further 
investigation. 

One  important  point,  however,  is  clearly  established  by  Burt's 
engine,  figs.  156,  157,  and  158,  that  flame  gases  do  not  lose  much 
heat  when  passed  from  cylinder  to  cylinder  by  short  open  ports. 
Experiments  made  by  the  author  also  bear  this  out.  Compound- 
ing to  be  successful  must  be  carried  out  by  means  of  very  short 
straight  and  unobstructed  ports. 


PART   III. 
OIL  ENGINES. 

CHAPTER   I. 

PETROLEUM    AND    PARAFFIN    OILS. 

OIL  engines  resemble  gas  engines  in  this,  that  the  power  is  gene- 
rated by  the  explosion  of  a  compressed  inflammable  gaseous 
mixture  in  an  engine  operating  according  to  the  well-known  Otto 
cycle. 

In  the  older  gas  engine  patents  it  was  customary  to  assume 
that  a  gas  engine  was  necessarily  an  oil  engine  also,  and  that  only 
trifling  additions  or  modifications  were  required  in  order  to  con- 
vert any  gas  engine  into  an  oil  or  inflammable  vapour  engine. 

For  many  years,  however,  the  difficulty  of  using  safe  oil  and 
producing  compressed  explosive  mixtures  from  it  was  so  great  that 
no  effective  oil  engine  was  placed  upon  the  market.  Even  now 
the  oil  engine  is  a  much  more  tricky  machine  than  the  gas  engine, 
although  it  is  more  reliable  than  was  formerly  the  case,  and  it  is 
rapidly  settling  down  by  the  industry  and  experiments  of  many 
inventors  to  something  like  a  standard  type. 

In  the  earlier  oil  engines  very  light  inflammable  oils  of  the 
gasoline  kind  were  used  to  supply  the  engine  with  inflammable 
vapour,  and  in  these  the  problem  of  vaporising  the  oil  was  com- 
paratively simple.  It  was  only  necessary  to  draw  air  over  a  surface 
saturated  with  gasoline  or  some  lighter  oil,  to  produce  a  mixture 
of  inflammable  vapour  and  air,  which  when  taken  into  the  cylinder 
of  a  gas  engine  readily  supplied  the  place  of  the  ordinary  coal 
gas,  and  gave  explosions  under  compression  closely  resembling 
those  obtained  with  coal  gas.  The  legal  restrictions  placed  upon 

c  c  2 


388  Oil  Engines 

the  carriage  and  storage  of  such  light  oils,  however,  made  it 
impossible  for  engines  using  only  such  oils  to  be  applied  exten- 
sively in  this  country,  and  accordingly  it  became  necessary  to 
devise  engines  with  vaporisers  of  a  kind  capable  of  supplying 
inflammable  vapours  of  gases  to  an  engine  using  oil  such  as  is 
commonly  adopted  for  petroleum  or  paraffin  lamps.  Such  oils  are 
much  less  volatile  than  the  gasoline  oils  already  mentioned,  and 
accordingly  it  is  much  more  difficult  to  produce  from  them 
inflammable  vapours  capable  of  exploding  in  a  gas  engine 
cylinder. 

The  object  of  the  engineer  in  dealing  with  those  heavier  oils 
is  to  so  treat  them  as  to  charge  the  engine  cylinder  with  an 
inflammable  mixture  of  air,  and  the  particular  hydrocarbon,  which 
mixture  is  sufficiently  stable  in  the  gaseous  or  vapour  state  to  stand 
compression  without  liquefaction.  At  the  same  time  the  explosion 
obtained  should  be  powerful  and  regular,  and  the  combustion  so 
complete  as  to  avoid  deposits  capable  of  clogging  the  valves  and 
working  parts. 

Many  difficulties  have  been  found  in  so  vaporising  oils  as  to 
produce  a  suitable  inflammable  mixture,  and  at  the  same  time 
avoid  clogging  up  the  vaporiser  or  the  engine. 

A  knowledge  of  the  properties  of  the  principal  hydrocarbons 
used  will  assist  the  engineer  in  deciding  between  differing  methods 
of  procedure,  and  accordingly  the  author  will  now  describe  and 
discuss  the  properties  of  the  various  hydrocarbon  oils  from  the 
point  of  view  of  the  oil  engine  inventor  or  designer. 

Chemistry  of  Petroleum  and  Paraffin  Oils. — A  few  words  will 
first  be  necessary,  however,  on  the  chemistry  of  petroleum  and 
paraffin.  The  oils  used  for  petroleum  engine  purposes  consist 
mainly  of  three  varieties — American  petroleum,  Russian  petroleum, 
and  Scotch  paraffin  oil. 

The  American  and  Russian  petroleum  is  obtained  by  refining 
crude  oil  which  issues  from  oil  wells  found  in  the  United  States 
of  America,  and  in  Russia  on  the  shores  of  the  Caspian  Sea. 

Crude  petroleum,  as  it  issues  from  the  wells,  is  a  mixture  of 
many  different  substances,  some  gaseous,  some  liquid,  and  some 
solid  ;  the  crude  petroleum  is,  in  fact,  a  liquid  containing  various 
gases  in  solution,  and  various  solid  bodies  as  well.  The  various 


Petroleum  and  Paraffin  Oils  389 

liquids,  solids  and  gases,  however,  resemble  each  other  in  one 
particular.  They  are  every  one  of  them  hydrocarbons,  that  is 
chemical  compounds  of  which  hydrogen  and  carbon  are  the  sole 
constituents. 

American  petroleum  consists  principally  of  hydrocarbons  be- 
longing to  a  chemical  series  known  as  the  paraffin  series.  This 
series  has  the  general  formula  CnH2n+2.  Members  of  another 
chemical  series,  however,  are  mixed  with  the  paraffin  group. 
This  other  series  is  known  as  the  olefine  series,  and  the  general 
formula  is  CnH2n. 

Both  the  paraffin  and  the  olefine  series  comprise  substances 
ranging  from  the  gaseous  state  to  the  solid  state  ;  that  is,  each  series 
contains  substances  which  are  solid,  substances  which  are  liquid, 
and  substances  which  are  gaseous. 

The  lightest  member  of  the  paraffin  series  is  the  well-known 
marsh  gas  methane  (CH4),  and  one  of  the  heaviest  of  the  liquid 
products  is  known  as  pentadecane,  C^Hgg,  and  the  solid  paraffin 
so  well  known  in  commerce  in  the  form  of  paraffin  candles  is  a 
mixture  consisting  principally  of  solid  members  of  the  paraffin  series, 
together  with  some  solid  members  of  the  olefine  series.  The 
olefine  series  likewise  comprises  a  whole  range  of  compounds 
beginning  with  the  well-known  gas  ethylene  (olefiant  gas),  and 
terminating  with  solid  olefines  containing  more  than  20  equi- 
valents of  carbon  to  40  equivalents  of  hydrogen. 

Crude  Pennsylvania  petroleum  as  it  issues  from  the  wells 
gives  off  as  gases  : 

Methane  (Marsh  Gas) C  H4 

Ethane Q>H6 

Propane     .....•••     QjHg 

and  12  separate  hydrocarbons  of  the  paraffin  series  have  been 
isolated  from  the  crude  liquid.  These  twelve  hydrocarbons  are 
given  in  the  table  on  page  390  with  formulae,  specific  gravity,  and 
boiling  point  of  each. 

All  these  hydrocarbons,  except  the  first,  are  liquid  at  ordinary 
temperatures.  The  boiling  points  of  the  hydrocarbons  vary  from 
o°  C.  to  260°  C.,  and  the  specific  gravity  from  '65  to  792. 

It  will  be  observed  that  in  every  one  of  these  compounds  the 
hydrogen  atoms  going  to  form  the  molecule  are  double  the 


390 


Oil  Engines 


number  of  the  carbon  atoms,  plus  an  additional  two  hydrogen 
atoms.  Marsh  gas,  for  example,  has  in  the  molecule  i  atom  car- 
bon, and  2  atoms  hydrogen  +  2.  Ethane  has  2  atoms  carbon, 
and  4  atoms  hydrogen  +  2,  that  is  6.  The  same  proportion  is 
given  in  all  the  members  of  the  series  in  the  table. 

SOME  HYDROCARBONS  OF  THE  PARAFFIN  SERIES 
FOUND  IN    PENNSYLVANIA  PETROLEUM.     (REDWOOD.) 


Name 

Formula 

Specific  Gravity 

Boiling  Point 

Normal 

Normal           Iso. 

Butane  .... 

C^Hjg 

0-645  at    o°  C. 

o°  C. 

Pentane 

C5H13 

0-645  •>    °°  C- 

38°  C.         30°  C. 

Hexane  .... 

CeHi4 

0-63    ,,  17°  C. 

t9°  C.         61°  C. 

Heptane 

CyHig 

0712  „  i6D  C. 

98J  C.         91°  C. 

Octane  .... 

CgH18 

0*726 

124°  C.       118°  C. 

Boiling  Point 

Nonane. 

Q  H.20 

071    at  15°  C. 

136°  to  138°  C. 

Decane  .... 

CioHga 

0757  ..  I5°C. 

160°  ,,   162°  C. 

Endecane 

CnH,4 

0765  ,,  16°  C. 

i8c°  „  184°  C. 

Dodecane 

C,oH.,6 

0766  ,,  20°  C. 

196°  ,,  200°  C. 

Tridecane 

C  is  Hgs 

O792  ,,   20°  C. 

216°  „  218°  C. 

Tetradecane  . 

CuHso 

236°  „  240°  C. 

Pentadecane  . 

C15H« 

255  J  ,,  260°  C. 

Pentadecane,  the  highest  here  shown,  has  15  atoms  carbon 
associated  with  30  +  2  atoms  of  hydrogen. 

The  hydrocarbons  of  this  series  resemble  each  other  very 
much  in  chemical  and  physical  properties.  They  decompose 
under  the  action  of  heat  in  a  similar  manner,  and  they  have 
similar  physical  properties.  Chemists  call  such  a  series  of  com- 
pounds a  homologous  series. 

The  American  refined  lamp  oils  of  .commerce  consist  prin- 
cipally of  the  heavier  hydrocarbons  given  in  the  list,  but  they  also 
contain  in  smaller  quantity  hydrocarbons  of  the  olefine  series. 

The  table  on  page  391  gives  a  few  of  the  best  known  mem- 
bers of  this  series. 

These  compounds  form  what  chemists  call  an  isomeric  series, 
because,  as  will  be  observed,  they  are  all  of  the  same  percentage 
composition.  Each  hydrocarbon  of  the  series  contains  exactly 
the  same  proportion  of  hydrogen  and  carbon,  namely,  857  carbon 
to  14-3  hydrogen.  The  compounds,  however,  differ  in  molecular 
density,  and  this  is  found  by  the  increasing  vapour  density  ; 


Petroleum  and  Paraffin  Oils  391 

thus,  if  one  volume  of  ethylene  be  taken  as  the  unit  of  weight, 
an  equal  volume  of  butylene  weighs  2,  hexylene  3,  and  so  on. 


SOME  MEMBERS  OF  THE  OLEFINE  SERIES. 


Ethylene  (Olefiant  Gas) 

Propylene 

Butylene    . 

Amylene    . 

Hexylene  . 

Heptylene 

Octylene    . 

Diamylene 

Triaraylene 

Tetramylene 


Boiling  Point 
Gaseous 


CH 


4°C. 

•       73°  C. 

.       70°  C. 

.       84°  C. 

.     119°  C. 

.  165°  C. 
C15H50  .  .  248°  C. 
^20^40  .  above  390°  C. 


C7H, 
CaH, 


Specific  Gravity 


0714  at  o°  C. 
0777  at  o°  C. 


The  term  isomer  is  sometimes  limited  to  compounds  of  the 
same  molecular  density  as  well  as  the  same  percentage  composi- 
tion. Such  compounds,  however,  differ  in  physical  and  chemical 
properties. 

At  first  it  is  very  surprising  to  find  that  two  chemical  substances 
of  identical  chemical  composition  and  molecular  density,  that  is, 
with  the  exact  proportions  of  the  element  present,  the  same  in 
both,  should  have  different  properties,  but  the  case  is  strictly 
analogous  to  what  is  known  of  the  elements.  Many  chemical 
elements  are  known  to  exist  in  several  forms,  without  change  of 
chemical  composition.  Carbon  exists,  for  example,  in  three  forms, 
the  diamond,  graphite,  and  charcoal.  These  three  forms  are 
widely  different  in  appearance  and  physical  properties,  but  each 
contains  nothing  but  carbon,  and  produces  nothing  but  carbonic 
acid  on  burning. 

Phosphorus  also  exists  in  two  forms,  yellow  and  red,  and  it 
is  more  than  suspected  that  iron  exists  in  several  forms. 

When  elements  vary  in  this  way,  the  variations  from  the  best 
known  form  are  called  allotropes  or  allotrofic  modifications. 
When  a  chemical  compound  has  several  varieties,  the  variations 
are  known  as  isomers.  The  word  isomer,  however,  is  more  strictly 
used  to  denote  compounds  not  only  of  the  same  percentage 
composition,  but  of  the  same  molecular  weight. 

Bodies   of  the   same   percentage   composition   and   different 


3Q2  Oil  Engines 

molecular   weights   are   known  as  polymers.     The  olefine  series 
then  are  polymers. 

The  oleftnes  are  present  in  American  petroleum  to  only  a 
small  extent,  but  in  Russian  petroleum  they  form  the  principal 
constituents.  The  hydrocarbons  present  in  Russian  petroleum 
are  not  quite  the  same  as  the  normal  olefines,  but  appear  to  be 
isomeric  modifications  of  the  true  olefine  series,  having  the 
general  form  of  CnH.;n_6KG.  This  formula  seems  to  be  a  round- 
about way  of  expressing  the  same  thing  as  CnH,n,  because  6H  is 
deducted,  and  6H  added.  It  is  not,  however,  the  same  form  as 
CnHon,  but  expresses  chemical  relationship  to  another  set  of  com- 
pounds. The  compounds  of  the  general  form  CnH2n_6Hfi  are 
called  naphthenes,  and  the  naphthenes,  although  of  the  same  per- 
centage composition  as  the  olerlnes,  resemble  the  paraffins  more 
closely  in  their  chemical  decompositions.  The  naphthenes,  which 
have  been  isolated  from  Russian  petroleums,  are  according  to 
Redmond  as  follows  : 

NAPHTHENES  ISOLATED  FROM  RUSSIAN  PETROLEUM. 

C8H16     .        .        .     119°  C  C12Ho4     .        .        .     196°  C. 

C,  H18      .        .        .     136°  C.  C14Ho8     .        .        .     240°  C. 

C10H,0     .         .         .     i6i°C.  C16H30     .         .         .     247°  C. 
CuHoo      .         .         .     i8o°C. 

The  specific  gravity  of  the  first-mentioned  hydrocarbon 
octonaphthene,  CSH16,  at  o°  C.  is  7714,  and  that  of  dodeca- 
naphthene  at  17°  C.  is  '8027. 

Paraffin  oil,  as  its  name  implies,  is  mostly  composed  of 
members  of  the  paraffin  series,  and  it  is  produced  by  the  destruc- 
tive distillation  of  Scottish  shale.  The  crude  oil  obtained  from 
the  retorts  contains,  like  petroleum,  substances  both  solid,  liquid, 
and  gaseous.  The  solid  paraffin  of  commerce  is  generally  obtained 
trom  this  paraffin  oil. 

The  chemistry  of  petroleum  and  paraffin  oils  is  extremely 
complex,  and  only  a  general  idea  has  been  here  given  of  the  main 
constituents. 

Before  leaving  the  chemistry,  it  is  desirable  to  consider  the 
decompositions  of  these  compounds  by  heat.  It  is  found,  for 
example,  that  if  a  heavy  member  of  the  paraffin  series  be  exposed 
to  heat  under  pressure,  so  as  to  attain  a  temperature  higher  than 


Petroleum  and  Paraffin  Oils  393 

the  boiling  point,  then  that  compound  decomposes  into  a  lower 
paraffin  and  an  olefine.  The  paraffin  hydrocarbon  C12H26,  for 
example,  may  be  decomposed  into  hexylene  C6H]2,  and  hexane 
C6H14.  The  reaction  may  be  taken  as  follows  : 


The  heavier  hydrocarbon  thus  splits  up  into  a  paraffin  and  an 
ethylene  containing  a  smaller  number  of  carbon  and  hydrogen 
equivalents  to  the  molecule.  It  depends  entirely,  however,  on 
the  particular  temperature  and  treatment  as  to  the  actual  decom- 
position which  will  take  place.  If  the  temperature  of  the  hydro- 
carbon be  raised  to  a  high  enough  point,  marsh  gas,  CH,,  can  be 
produced,  and  carbon  left  in  the  retort.  The  olefines  decompose 
also,  heavier  olefines  producing  lighter  olefines  by  the  influence 
of  heat,  or  lighter  olefines  together  with  hydrogen,  marsh  gas,  and 
solid  carbon  deposit. 

Petrole.um  Ether  and  Spirit. — The  volatile  liquids  produced 
from  American  petroleum  have  been  classed  as  petroleum  ether 
and  petroleum  spirit.  The  following  table  gives  a  list  of  the 
substances  so  produced.  The  names  given  are  not  chemical 
names,  but  ordinary  trade  names,  and  the  compounds  are  not 
pure  hydrocarbons  of  one  composition,  but  mixtures  of  hydro- 
carbons boiling  at  very  low  points. 

PETROLEUM  ETHER  AND  SPIRIT. 


Specific  Gravity 

Petroleum  Ether     . 
Petroleum  Spirit 

1  i.   Cymogene    . 
\  2.   Rhizoline 
(  3.   Gasoline 
/  4.   C  Naphtha  (Benzine  Naphtha) 
J  5.   B  Naphtha 
(6.  A  Naphtha  (Benzine) 

•590 
•625  to  -631 
•635  ,,   '666 
•678  ,,   700 
714  ,,   718 
74i  ••   745 

According  to  Mr.  Alfred  H.  Allen,  cymogene  consists  chiefly 
of  butane,  C,Hin,  of  pentane,  C5H12,  and  an  isomer  of  that 
substance  ;  and  hexylene,  C6H1?,  and  an  isomer  of  hexylene. 

As  these  products  are  extremely  volatile,  cymogene  boiling  at 
o°  C.,  the  freezing  point  of  water,  and  the  heaviest  A  naphtha 
boiling  away  under  70°  C.,  it  follows  that  they  are  dangerous  to 
handle,  and  are  far  too  inflammable  for  general  use  in  oil  engines. 


394  Oil  Engines 

The  substance  cymogene,  for  example,  could  only  be  retained  in 
the  liquid  state  permanently  by  means  of  a  freezing  mixture,  and 
all  the  others  are  so  volatile  that  it  would  be  dangerous  to 
approach  an  open  vessel  containing  them  with  a  light.  Any  one 
of  these  liquids  would  go  on  fire  instantaneously  on  plunging  a 
lighted  match  or  taper  into  the  liquid.  Liquid  so  inflammable ' 
and  so  capable  of  producing  large  volumes  of  explosive  mixture 
are  much  too  dangerous  for  successful  use  by  the  general  public 
in  engines. 

The  whole  of  these  liquids  are  clear  limpid  fluids,  having 
when  pure  a  rather  agreeable  odour. 

Petroleum  and  Paraffin  burning  Oils  sold  in  Britain. — The 
oils  which  really  concern  the  engineer  designing  petroleum 
engines  are  not  the  crude  oils  or  the  petroleum  spirit  or  ether, 
but  the  burning  oils  which  are  sold  in  Britain  in  a  condition 
sufficiently  safe  to  be  used  in  ordinary  lamps.  The  Petroleum 
Act  of  1876,  and  its  subsequent  modification  in  1879,  determines, 
that  oils  sold  for  illuminating  purposes  shall  not  have  a  flashing 
point  less  than  73°  F.,  the  flashing  point  to  be  determined  by  a 
special  apparatus  fully  described  in  the  Act.  The  apparatus  and 
the  method  of  manipulating  it  are  the  work  of  Sir  Frederic 
Abel,  so  that  the  standard  test  for  these  oils  for  flashing  point  is 
known  as  the  Abel  test. 

Fig.  181  is  a  section  of  the  Abel  close  test  apparatus,  from 
which  it  will  be  seen  that  a  copper  vessel  c  is  provided  which 
contains  water  marked  w.  This  water  forms  a  water  bath.  An 
air  chamber  A  is  placed  within  the  water  bath,  and  it  carries 
within  it  an  oil  cup  p  made  of  gun  metal.  This  cup  rests  upon  an 
ebonite  ring,  and  over  the  air  chamber  A,  and  has  a  tight-fitting  lid 
on  which  is  fixed  a  gas  burner.  The  oil  cup  carries  a  thermo- 
meter /,  and  above  the  cover  is  fixed  a  slide,  which  slide  on 
being  moved  is  caused  to  uncover  three  holes.  The  gas  jet 
swivelling  on  a  lever,  and  moving  with  the  movement  of  the 
slide,  carries  a  small  flame,  and  the  movement  is  so  combined 
that,  as  the  lever  tilts,  the  flame  is  passed  through  one  of  the 
openings  in  the  slide  and  reaches  the  top  of  the  oil  in  the  oil 
cup. 

The  thermometer  /'  is  intended  to  take  the  temperature  of  the 


Petroleum  and  Paraffin  Oils 


395 


water  bath,  and  the  spirit  lamp  b  supplies  the  necessary  heat. 
The  pendulum  shown  alongside  of  the  apparatus  is  24  inches 
long,  and  is  intended  to  time  the  operation  of  testing  the  flash. 

To  determine  the  flashing  point  of  the  oil,  the  temperature  of 
the  water  bath  at  the  start  of  the  test  is  arranged  at  exactly  130°  F. 
The  oil  to  be  tested  is  cooled  to  60°  F.  and  poured  carefully  into 
the  oil  cup  P,  avoiding  splashing,  until  the  oil  reaches  the  point  of 
a  small  bent  wire  gauge  inside  the  cup.  The  lid  is  then  put  on, 
and  the  cup  placed  in  the  bath,  the  rise  of  the  temperature  being 


FIG.  1 8 1.— Abel  Flash  Test  Apparatus. 

watched  on  the  thermometer  /  in  the  petroleum  cup.  When  the 
oil  reaches  the  temperature  of  66°  F.  the  testing  is  started  by 
setting  the  pendulum  in  motion,  and  while  it  makes  three  oscilla- 
tions, drawing  the  slide  slowly  open,  and  at  the  fourth  oscillation 
closing  it  rapidly.  By  this  the  test  flame  is  gently  tilted  through 
a  hole  in  the  slide  to  the  space  above  the  oil.  This  operation  is 
repeated  once  for  every  increase  of  temperature  of  i°  F.  until  the 
vapour  of  the  oil  ignites  within  the  oil  cup,  giving  a  pale  blue 
flicker  or  flash.  The  temperature  of  the  oil  at  which  this  occurs 
is  called  the  flashing  point  ;  that  is,  the  flashing  point  is  that 


396  Oil  Engines 

temperature  at  which  the  oil  gives  off  sufficient  vapour  to  be 
ignited  by  a  flame.  The  lowest  flashing  point  allowed  by  law  for 
petroleum  intended  for  burning  lamps  in  this  country  is  73°  F.  or 
22-8°  C.  It  is  very  important,  therefore,  in  experimenting  upon 
various  samples  of  oil,  to  make  certain  that  the  oil  is  above  the 
legal  flashing  point. 

Other  qualities  are  also  necessary,  and  these  can  be  determined 
by  the  specific  gravity  of  the  oil,  and  by  the  distillation  of  the  oil, 
and  observation  as  to  the  range  of  temperature  during  which  the 
oil  boils  over. 

The  ordinary  burning  oils  sold  in  Britain  are  American  oils, 
Royal  Daylight,  Ordinary,  Water  White,  and  Tea  Rose. 

The  Russian  oils  are  Russoline  and  Russian  Lustre. 

The  paraffin  oils  are  Broxbourne  Lighthouse,  Young's  paraffin 
oil,  and  similar  oils  by  many  other  makers. 

Professor  Robinson  has  made  an  interesting  series  of  experi- 
ments upon  the  principal  burning  oils  sold  in  Britain,  and  he  has 
determined  the  specific  gravity  flashing  point  by  Abel's  test,  the 
point  at  which  each  oil  begins  to  boil,  and  the  percentage  distilled 
between  certain  ranges  of  temperature.  He  has  also  made  deter- 
minations of  the  specific  heat,  and  the  co-efficients  of  expansions 
of  several  of  the  oils. 

The  opposite  table  gives  a  summary  of  his  results. 

From  this  table  it  will  be  seen  that  the  burning  oil  with  the 
lowest  flashing  point  is  American  Ordinary,  which  has  a  light  straw 
colour,  a  specific  gravity  of  791,  and  was  sold  some  time  ago  at 
$\d.  per  gallon.  This  oil  begins  to  boil  at  145°  C.  ;  at  215°  C. 
29  per  cent,  of  the  oil  distils  over  to  the  condenser  ;  and  at  233°  C. 
36  per  cent,  distils.  To  vaporise  the  entire  oil,  therefore,  required 
a  temperature  above  233°  C. 

Looking  at  the  table,  Royal  Daylight  oil  begins  to  boil  at  144° 
C.  ;  and  when  the  thermometer  reaches  215°  C.  25  per  cent,  of  the 
liquid  is  distilled.  At  230°  C.  35  per  cent,  is  distilled.  At  300°  C. 
Professor  Robinson  states  in  another  part  of  his  paper  that  76 
per  cent,  boils  over,  and  at  340°  C.  82  per  cent.  At  358°  C.,  the 
extreme  limit  of  the  thermometer  used,  there  was  still  a  consider- 
able residue.  The  Royal  Daylight  oil,  therefore,  contains  a  very 
wide  range  of  hydrocarbons,  beginning  probably  with  octane, 


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Intermediate  Oils. 
American  Mineral  Sperm  . 
Storrar's  Scotch  Gas  Oil  . 
Scotch  Intermediate  Shale  . 
Oil  .  .  .  ) 
Light  Lubricating  Oil 

398  Oil  Engines 

C5H18,  and  certainly  containing  towards  the  end  higher  hydro- 
carbons than  pentadecane,  C15H3.2. 

Another  American  burning  oil,  Water  White,  having  a  specific 
gravity  of  78,  has  a  flashing  point  of  108°  F.,  begins  to  boil  at 
150°  C,  and  at  215°  C.  55  per  cent,  boils  off. 

This  oil  is  evidently  of  simpler  composition  than  the  others  ; 
that  is,  it  contains  hydrocarbons  within  a  smaller  range  of  mole- 
cular weight. 

Russoline,  it  will  be  observed,  the  Russian  ordinary  burning 
oil,  begins  to  boil  at  151°  C.,  and  by  the  time  the  temperature  has 
reached  221°,  only  36  per  cent,  has  boiled  over.  The  flashing 
point,  therefore,  of  this  oil  is  high,  82°. 

Broxbourne  Lighthouse  oil  begins  to  boil  at  about  215°,  and  is 
completely  boiled  over  at  300°. 

From  these  experiments  it  appears  that  many  of  the  burning 
oils  of  commerce  are  so  constituted  that  even  at  so  high  a  tem- 
perature as  350°  C.,  part  of  the  oil  refuses  to  come  over. 

It  is  quite  evident  that  the  type  of  vaporisers  required  in  a  given 
case  must  be  largely  determined  by  the  nature  of  the  oil.  Thus  an 
engineer  working  with  Broxbourne  Lighthouse  oil  would  find  that 
he  succeeded  in  evaporating  the  whole  of  the  oil  at  300°  C.  by  the 
agency  of  heat  alone,  whereas  if  he  had  experimented  with  Ameri- 
can Ordinary  oil,  he  would  have  found  at  that  temperature  a  very 
large  residue  remaining  in  his  vaporiser. 

Methods  of  Vaporising  and  Decomposing. — Before  discussing 
the  vaporisers  in  actual  use,  it  is  advisable  to  consider  some  of 
the  laboratory  methods  of  vaporising,  in  view  of  the  difficulty  of 
providing  vaporisers  which  will  treat  varying  oils  of  high  flashing 
point  and  density. 

When  a  homogeneous  substance  like  water  is  boiled,  the  tem- 
perature remains  constant  from  the  moment  of  boiling  to  the  com- 
plete distillation  of  the  whole  liquid. 

Likewise  if  dry  air  be  blown  through  water,  every  cubic  foot  of 
air  will  carry  off  a  certain  volume  of  water  vapour,  until  the  whole 
of  the  water  is  evaporated,  and  this  will  occur  by  blowing  through 
air  at  any  temperature  at  which  water  has  an  appreciable  vapour 
tension. 

The  vapour  tension  of  water  is  the  pressure  of  water  vapour  at 


Tension 

Temp.  C. 

urn.  Mercury 

Temp.  C. 

0° 

. 

4-6 

40° 

5° 

5  '53 

50° 

10° 

. 

9-17 

60  D 

15° 

. 

12*70 

70° 

20° 

. 

i?  '39 

80° 

25° 

. 

23  '55 

90' 

30° 

. 

3I-55 

100° 

Petroleum  and  Paraffin  Oils  399 

any  given  temperature.     The  term  vapour  tension  is  generally  used 
for  pressures  under  atmospheric  pressure. 

The  following  table  gives  the  vapour  tension  of  water  for 
different  temperatures  from  o°  C.  to  100°  C.  The  tension  is  given 
in  millimetres  mercury  ;  that  is,  the  tension  of  the  water  vapour  at 
each  temperature  is  given  in  the  height  of  mercury  column  which 
the  particular  pressure  of  water  vapour  at  that  temperature  is  cap- 
able of  supporting. 

VAPOUR  TENTSION  OF  WATER  VAPOUR. 

Tension 
mm.  Mercury 

•  54'9I 
.        91  ^ 
.      14870 
.     233-09 
.      288-51 

•  525 '45 
.     760-00 

From  this  table  it  will  be  observed  that  at  15°  C.,  about  the 
ordinary  temperature  of  the  atmosphere,  the  tension  or  pressure  of 
water  vapour  is  equal  to  127  mm.  mercury.  The  total  pressure 
of  the  atmosphere  is  taken  as  760  mm.  mercury,  from  which  it 
would  appear  that  the  pressure  of  water  vapour  at  that  temperature 
is  about  ^5-  of  the  pressure  of  the  atmosphere,  so  that  if  water  were 
to  be  evaporated  by  passing  air  through  it  at  that  temperature, 
60  cb.  ft.  would  require  to  be  passed  through  to  take  away  i  cb.  ft. 
of  water  vapour,  that  is  to  take  away  a  volume  of  vapour  sufficient 
to  make  i  cb.  ft.  of  steam  supposed  to  be  at  atmospheric  pressure 
and  temperature.  If,  however,  the  temperature  be  raised  to  about 
80°  C.,  2  cb.  ft.  of  dry  air  would  carry  away  about  i  cb.  ft.  of  steam 
calculated  at  atmospheric  pressure. 

Water  can  thus  be  evaporated  either  by  boiling  it  off  by  raising 
the  temperature  above  the  boiling  point,  or  by  passing  air  through 
it  or  any  other  gas  at  a  temperature  below  the  boiling  point ;  and 
the  amount  carried  off  by  a  cubic  foot  of  air  depends  upon  the 
temperature  of  the  water. 

The  important  point  to  remember  is,  that  to  however  low  a 
temperature  the  water  be  reduced,  it  can  be  entirely  evaporated 
by  treatment  with  a  sufficient  volume  of  air. 


4OO  Oil  Engines 

Petroleum  or  oil  in  the  same  way  can  be  evaporated  either  by 
boiling  off,  or  by  treatment  with  air  or  gas  ;  and  the  temperature 
at  which  the  whole  liquid  can  be  evaporated  is  much  reduced  by- 
passing hot  air  over  the  liquid,  instead  of  attempting  to  boil  the 
liquid  away.  Thus  many  of  the  American  oils,  which  leave  a  con- 
siderable residue  at  358°  C,  could  easily  be  evaporated  bypassing 
hot  air  through  the  liquid,  without  requiring  any  further  rise  of 
temperature.  It  is  often  objectionable  to  attempt  to  vaporise  by 
boiling  off  or  distilling,  because  in  many  oils  the  boiling  point  is 
so  high  that  the  decomposition  point  is  reached  before  the  liquid 
will  boil.  In  such  a  case,  attempting  to  force  vaporisation  or  dis- 
tillation by  increasing  the  heat  only  results  in  the  chemical  decom- 
position of  the  oil,  and  leaving  in  the  vaporiser  a  comparatively 
large  quantity  of  carbon  or  tar.  A  sample,  for  example,  of  solid 
paraffin,  such  as  is  used  for  candles,  could  not  be  entirely  distilled 
by  any  attempt  at  boiling  ;  but  if  the  sample  be  placed  in  a  vessel, 
which  vessel  is  heated  to  the  highest  temperature  which  the  paraffin 
will  stand  without  decomposition  on  a  sand  bath — say  about 
400°  C. — and  super-heated  steam  be  blown  through  the  liquid 
paraffin,  then  nearly  the  whole  of  that  solid  paraffin  can  be  distilled 
without  decomposition.  From  this  it  follows  that,  if  vaporisation 
is  desired  without  decomposition,  the  temperature  can  be  kept 
much  lower  by  heating  the  vaporiser  to  a  predetermined  point, 
and  then  passing  hot  air  over  the  liquid  contained  in  it. 

It  is  interesting  to  note,  in  connection  with  the  decomposition 
of  paraffin  and  olefines  by  heat,  that  mere  heating  up  in  a  closed 
vessel  does  not  produce  any  large  amount  of  decomposition.  If, 
however,  the  oil  or  paraffin  be  heated  up  under  pressure  in  such 
manner  that  the  ordinary  boiling  point  is  considerably  exceeded, 
and  that  oil  be  distilled  and  condensed  in  a  condenser — also 
under  pressure — then  the  oil  rapidly  decomposes. 

Some  well-known  laboratory  methods  of  experimenting  illus- 
trate in  a  vivid  manner  the  various  facts  which  are  useful  to  the 
engineer  designing  oil  engines.  The  distillation  of  water,  for 
example,  in  the  laboratory  apparatus  shown  in  fig.  182,  and  the 
subsequent  distillation  of  oils  in  the  same  apparatus,  enables  one 
to  realise  the  difference  between  the  nature  of  oils  and  water. 

The  apparatus  is  very  simple,  and  consists  of  a  glass  flask  A 


Petroleum  and  Paraffin  Oils 


401 


having  a  tightly  fitting  cork  a,  through  which  passes  a  glass  T  piece 
b,  carrying  the  thermometer  B.  The  free  end  of  the  T  piece  slips 
into  the  glass  condenser  tube  c.  This  condenser  tube  passes 
within  a  water  jacket  tube  D,  fed  with  a  current  of  cold  water  by 
the  side  tube  c,  which  current  discharges  at  d.  The  condenser 
tube  terminates  in  the  glass  receiving  flask  E,  supported  upon  a 
retort  stand  ;  the  condenser  is  held  by  a  clamp,  also  supported  on 
a  retort  stand,  and  the  distilling  flask  rests  upon  wire  gauze  sup- 
ported on  a  tripod,  and  is  heated  by  a  Bunsen  flame. 

It  is  an  interesting  exercise  to  rig  up  this  apparatus,  and  distil 
fresh  water  from  the  flask,  observing  the  thermometer  during  the 


FlG.  182.— Distillation  of  Water. 

process.  Fresh  water  will  boil  away  to  the  last  drop,  and  collect 
in  the  receiving  flask  while  the  thermometer  remains  steady  at 
100°  C.  from  the  beginning  of  the  boiling  to  the  completion  of 
the  distillation. 

If  a  sample  of  Royal  Daylight  oil  be  placed  in  the  distilling 
flask  (carefully  dried  from  water),  it  will  be  found  that  the  oil 
begins  to  boil  about  144°  C.,  and  that  a  lighter  oil  first  passes  over, 
and  that  the  thermometer  slowly  rises,  so  that  at  340°  C.  only 
82  per  cent,  of  the  whole  had  distilled  over,  and  even  at  358°  C. 
a  considerable  liquid  residue  was  left  in  the  vessel.  If  the  receiving 
flask  be  frequently  changed  in  the  course  of  the  distillation,  oils 
of  different  densities  will  be  collected,  the  lighter  oils  boiling  off 

D  D 


402 


Oil  Engines 


first,  and  the  heavier  in  order  later.  Such  a  process  of  distillation 
is  called  fractional  distillation,  and  on  the  manufacturing  scale  it 
is  practised  to  purify  the  oils,  and  separate  the  light  from  the 
heavy.  In  making  this  experiment  with  oil,  the  apparatus  should 
be  modified  as  shown  in  fig.  183,  where  the  wire  gauze  is  replaced 
by  a  sand  bath,  in  order  to  protect  the  glass  flask  containing  oil 
from  the  direct  action  of  the  flame.  In  distilling  oils  experimentally 
from  glass  flasks,  it  is  well  to  limit  the  size  of  the  flask  not  to 
exceed  250  c.c.  (quarter  litre)  ;  and  a  quantity  of  dry  sand  should 
be  kept  at  hand  to  extinguish  the  oil  flame  if  the  flask  breaks  and 
ignites. 


FIG.  183.— Distillation  of  Oil. 

It  is  found  that  as  the  lighter  oils  distil  off  and  the  thermo- 
meter rises,  the  oil  in  the  distilling  flask  gradually  becomes  darker 
in  colour,  and  at  the  high  temperature  of  350°  C.  it  becomes  quite 
brown.  At  first  it  is  of  a  pale  straw  colour,  and  this  change  to 
brown  proves  chemical  decomposition  to  be  going  on. 

If  a  quantity  of  the  oil  which  refuses  to  boil  at  even  the  high 
temperature  of  350°  C.  be  placed  in  one  end  of  a  bent  glass  tube, 
c,  fig.  184,  and  the  tube  sealed  up  by  the  blowpipe  flame,  then 
the  liquid  distilled  from  the  end  a  into  the  end  b  without  apply- 
ing any  cooling,  but  after  distilling  returned  again  to  the  end  a 


Petroleum  and  Paraffin  Oils 


403 


and  distilled  to  b  again  ;  the  process  being  repeated  say  for 
about  twelve  times  ;  it  will  then  be  found  on  opening  the  glass 
tube  that  the  oil  subjected  to  this  distillation  under  pressure  has 
changed  its  nature  very  considerably.  This  can  easily  be  proved 
by  returning  it  to  the  flask  A,  fig.  183,  and  testing  the  boiling 
point.  It  is  then  found  that  the  liquid  which  before  refused  to 
boil  at  358°  C.  will  now  begin  to  boil  below  140°  C.  and  the  greater 
part  of  it  will  distil  over  long  before  300°  C.  is  reached. 

A  sample  of  the  same  heavy  oil  remaining  from  the  first  oil 
experiment  if  placed  in  a  straight  sealed  tube  as  A,  fig.  185,  may 


FIG.  184. — Decomposition  of  heavy  Oil. 

be  heated  and  cooled  to  the  same  extent  as  and  for  the  same  time 
as  with  the  bent  tube  in  fig.  184,  and  after  these  series  of  heatings 
and  coolings  it  will  be  found  to  have  hardly  changed  its  composi- 
tion. These  oils  if  merely  heated  under  pressure  without  distilla- 
tion can  bear  comparatively  high  temperatures  without  decomposi- 
tion, but  if  distilled  at  the  high  temperature  decomposition 
results. 

This  appears  due  to  the  recombination  of  the  oils  when  heated 
to  a  high  temperature  and  cooled  slowly.  For  effective  decom- 
position it  is  necessary  to  distil. 

The  American  petroleum  refiners  treat  the  heavy  oil  left  in  the 


404 


Oil  Engines 


still  after  distilling  off  the  light  and  the  burning  oils  by  a  process 
called  cracking.  The  still  is  formed  with  a  very  large  and  roomy 
head  which  causes  the  oil  to  condense  and  run  back  to  the  still, 
and  in  this  way  after  heating  for  a  considerable  time  it  is  found  that 
the  oil  is  cracked  and  oils  of  lower  boiling  point  produced.  The 
cracking  process,  however,  is  attended  with  the  separation  of  a 
proportion  of  solid  carbon. 

Professors   Boverton  Redwood  and    Dewar   have   devised   a 

method  of  distilling  oils  in 
a  compressed  gaseous  atmo- 
sphere which  appears  to  pro- 
duce more  rapid  and  perfect 
decomposition  from  heavier  to 
lighter  oils. 

If  the  thermometer  be 
removed  from  the  distilling 
flask,  fig.  183,  before  the 
temperature  rises  so  high  as 
to  damage  it,  and  the  heat  be 
further  raised,  it  is  found  that 
after  a  time  a  tarry  mass  is  left 
in  the  flask  which  cannot  be 
removed  by  heating.  These 
experiments  very  clearly  show 
that  the  particular  oil  could 
not  be  vaporised  by  boiling  off 
without  leaving  a  considerable 
residue.  It  would,  therefore, 
be  hopeless  with  this  oil  to 
design  a  vaporiser  to  boil  off  the  oil  as  vapour,  it  would  only  result 
in  the  vaporiser  being  choked  with  tar  and  carbon  deposit  in  a  few 
hours. 

Some  method  is  required  which  will  vaporise  the  whole  of 
this  heterogeneous  oil,  the  heavy  part  as  well  as  the  light.  This 
can  be  done  in  another  way  by  means  of  the  apparatus  shown  in 
fig.  1 86,  which  is  the  same  as  that  shown  in  fig.  183  except  that  the 
flask  A  has  a  wider  neck,  and  the  cork  carries  in  addition  to  the 
T  piece  and  thermometer  the  air  tube  D.  If  the  flask  A  be 


FIG.  185.  — Heating  heavy  Oil 
in  a  straight  tube. 


Petroleum  and  Paraffin  Oils  405 

charged  with  Daylight  oil  and  heated  up  to  about  140°,  then  air 
be  slowly  bubbled  through  the  oil  (from  a  gasometer),  it  will 
be  found  that  the  whole  of  the  oil  can  be  distilled  out  of  the 
flask  A  without  leaving  any  heavy  residue,  and  the  temperature  of 
the  thermometer  need  not  be  raised  above  200°  C.  In  this  case 
almost  the  whole  of  the  contents  of  the  flask  will  pass  over  with- 
out decomposition  and  without  leaving  any  clogging  residue  or 
carrying  over  any  tarry  matter. 

If  a  sample  of  solid  paraffin  be  placed  in  the  flask  fig,  186  and 
heated  up  to  about  350°,  then  dry  steam  be  blown  through  by  the 


FIG.  186. — Distillation  of  Oil  or  Paraffin  by  Air  or  Steam. 

pipe  D,  it  will  be  found  that  even  solid  paraffin  will  distil  over 
practically  without  decomposition. 

If  the  paraffin  be  heated  highly  alone  and  distillation  attempted, 
it  rapidly  decomposes,  leaving  a  charred  carbon  mass. 

From  these  experiments  it  is  evident  that  the  best  method 
of  vaporising  a  hydrocarbon  oil  containing  heavy  as  well  as  light 
hydrocarbons  is  to  heat  the  oil  in  a  vaporiser  to  a  moderate 
temperature,  say  about  300°  C.,  and  then  pass  air  over  it  also 
heated  to  about  the  same  temperature.  By  treating  it  in  this 
way  the  whole  of  the  oil,  light  and  heavy,  can  be  vaporised 
without  fear  of  decomposing  the  oil  and  so  producing  tarry 
products  or  carbon  residues. 


406  Oil  Engines 

It  is  a  mistake  to  use  red-hot  surfaces  in  vaporising  an  oil 
when  the  vapour  formed  has  to  pass  through  valves  ;  it  is  a 
mistake,  however,  which  inventors  often  make. 

An  oil  like  'Broxbourne  Lighthouse'  boiling  entirely  below 
300°  C.  might  be  treated  in  another  way,  but  the  method  described 
of  passing  hoi  air  through  would  easily  vaporise  it  also,  so  that  no 
other  method  is  necessary. 

The  methods  of  distilling  or  boiling  under  reduced  pressure 
also  supply  means  of  vaporising  oil  at  comparatively  low  tempera- 
tures ;  but  the  vacuum  pan  system,  although  largely  applied  to  the 
sugar  industry,  has  not  been  applied  to  the  vaporising  of  oils. 


407 


CHAPTER   II. 

OIL   ENGINES. 

HAVING  now  discussed  briefly  the  chemical  and  physical  properties 
of  the  hydrocarbon  oils,  the  reader  is  in  a  position  to  consider  the 
mechanical  arrangements  of  oil  engines.  The  lighter  oils  being  so 
easily  vaporised  were  naturally  first  used  in  the  early  forms  of  oil 
engine.  With  oils  of  a  specific  gravity  less  than  74  and  a  flashing 
point  as  a  rule  lower  than  the  ordinary  atmospheric  temperature 
of  1 6°  C.,  such  as  benzine,  benzine  naphtha  and  gasoline,  the  problem 
of  producing  an  inflammable  mixture  capable  of  being  drawn  into 
an  engine  cylinder,  compressed  and  exploded,  is  so  simple  that  no 
complicated  considerations  trouble  the  inventor  in  producing  his 
engine.  The  earlier  oil  engines  accordingly  used  such  light  oils. 

Early  Oil  Engines. — The  earliest  proposal  to  use  oil  as  a  means 
of  producing  motive  power  by  explosion  appears  to  be  that  of 
Street,  whose  English  patent  was  taken  out  in  the  year  1791. 
The  first  practical  petroleum  engine,  however,  was  that  of  Julius 
Hock  of  Vienna,  who  produced  an  engine  in  1870.  This  engine 
operated  on  the  old  non -compression  system  and  took  in  a  charge 
of  air  and  light  petroleum  spray  during  part  of  the  forward  stroke 
of  a  piston,  ignited  that  charge  at  atmospheric  pressure  by  means 
of  a  flame  jet  and  so  produced  a  low-pressure  explosion  similar  to 
that  of  the  Lenoir  gas  engine.  In  1873  Brayton,  an  American 
engineer,  produced  an  oil  engine  shown  on  p.  152  of  this  work.  In 
that  engine  heavy  oil,  it  is  true,  was  used  having  a  density  some- 
times as  high  as  '85,  but  this  oil  was  crude  unrefined  oil  flashing  at 
about  atmospheric  temperature.  The  engine  was  not  a  practical 
success,  but  it  was  the  first  compression  engine  using  oil  fuel 
instead  of  gas. 


Oil  Engines 

Shortly  after  the  Otto  gas  engine  came  into  use  in  1876, 
several  engines  of  that  type  were  operated  by  air  gas,  a  gas  pro- 
duced from  the  liquid  known  as  gasoline,  by  drawing  air  through 
the  gasoline  and  so  charging  this  air  with  inflammable  vapour.  The 
air  so  charged  was  drawn  into  the  engine  cylinder  with  a  further 
supply  of  air  and  formed  an  explosive  mixture,  which  was  com- 
pressed and  ignited  in  the  usual  manner  common  to  Otto  cycle 
engines. 

The  Spiel  petroleum  engine  appears  to  be  the  first  engine  of 
the  Otto  cycle  introduced  into  practice  which  dispensed  with  an 
independent  vaporising  apparatus.  In  this  engine  light  oil  of  not 
greater  than  725  specific  gravity  was  injected  directly  into  the 
cylinder  on  the  suction  stroke,  and  mixing  with  the  air  entering 
the  whole  of  the  oil  became  vaporised  at  ordinary  temperatures 
or  at  the  slightly  increased  temperature  of  the  engine  cylinder,  and 
on  compression  an  explosive  mixture  was  obtained  which  acted 
precisely  as  the  ordinary  gas  mixture  of  the  Otto  engine.  Good 
results  are  obtained  by  the  Spiel  engine  so  far  as  economy  is 
concerned,  the  consumption  being  *8i  Ib.  per  brake  HP  per 
hour.  The  engine,  however,  never  became  really  popular  because 
such  light  oils  as  it  used  were  dangerous,  and  besides  legal 
restrictions  as  to  storage  and  transport  of  light  oils  materially 
interfere  with  the  introduction  of  such  an  engine. 

Engines  using  safe  burning  Oils. — Safe  burning  oils  having  a 
flashing  point  above  73°  F.  require  very  different  treatment  to 
obtain  an  explosive  mixture  capable  of  operating  an  oil  engine, 
and  the  treatment  required  varies  with  the  nature  of  each  particular 
sample  of  oil.  Engines  now  constructed  use  American  and  Russian 
petroleums  and  Scotch  paraffin  oils  without  difficulty.  Such  oils 
vary  in  specific  gravity  from  78  to  '825  and  in  flashing  point 
from  75°  to  152°  F.  All  of  the  oils  in  ordinary  use  have,  as 
has  been  already  pointed  out,  different  temperatures  at  which 
they  begin  to  boil  at  ordinary  atmospheric  pressure.  The 
temperatures  vary  from  144°  C.  to  165°  C.  (see  table,  p.  397). 
Engines  burning  such  oils  may  be  divided  into  three  distinct 
classes  : 

i  st.  Engines  in  which  the  oil  is  subjected  to  a  spraying  opera- 
tion before  vaporising. 


Oil  Engines  409 

2nd.  Engines  in  which  the  oil  is  injected  into  the  cylinder  and 
vaporised  within  the  cylinder. 

3rd.  Engines  in  which  the  oil  is  vaporised  in  a  device  exter- 
nal to  the  cylinder,  and  introduced  into  the  cylinder  in  the  state 
of  vapour. 

This  division  into  three  classes  thus  refers  to  the  mode  of 
vaporising.  The  method  of  ignition  may  also  be  used  to  divide 
the  engines  into  different  classes  : 

i st.  Oil  engines  igniting  by  the  electric  spark. 

2nd.  Oil  engines  ignited  by  incandescent  tube. 

3rd.  Oil  engines  igniting  by  the  heat  of  the  internal  surfaces  of 
the  combustion  space. 

Spiel's  engine  was  ignited  by  means  of  a  flame-igniting  device 
similar  to  that  used  in  Clerk's  gas  engine  described  on  p.  215  of 
this  work,  but  Spiel's  engine  is  the  only  one  introduced  into  this 
country  which  ever  used  a  flame  igniter.  On  the  Continent,  how- 
ever, flame  igniters  are  not  uncommon.  Hille's  engine  uses  a 
flame  igniter.  In  this  country,  however,  all  methods  of  ignition 
both  in  gas  and  oil  engines  have  for  practical  purposes  been  dis- 
placed by  the  hot  tube  and  the  hot  surface  igniters. 

Engines  in  which  the  Oil  is  subjected  to  a  Spraying  Operation 
before  Vaporising. — The  engines  at  present  in  use  in  this  country 
falling  under  this  head  are  the  Priestman  and  the  Samuelson.  In 
both  the  oil  is  sprayed  before  being  vaporised.  The  principle 
of  the  spray  producer  used  is  that  so  well  and  widely  known  in 
connection  with  the  atomisers  or  spray  producers  used  by  per- 
fumers. Fig.  187  shows  such  a  spray  producer  in  section.  In 
this  elementary  form  of  spray  producer  an  air  blast  passing  from 
the  small  jet  A  crosses  the  top  of  the  tube  B,  and  creates  within 
that  tube  a  partial  vacuum.  The  liquid  contained  in  the  glass 
bottle  c  flows  up  the  tube  B,  and  issuing  at  the  top  of  the  tube 
through  a  small  orifice  is  at  once  blown  into  very  fine  spray  by 
the  action  of  the  air  jet.  If  such  a  scent  distributor  be  filled 
with  petroleum  oil  such  as  Royal  Daylight  or  Russoline,  the  oil 
will  also  be  blown  into  fine  spray,  and  it  will  be  found  that  this 
spray  can  be  ignited  by  a  flame  and  will  burn,  if  the  jets  be  pro- 
perly proportioned,  with  an  intense  blue  non-luminous  flame. 
The  earlier  inventors  often  expressed  the  idea  that  an  explosive 


Oil  Engines 


mixture  could  be  prepared  without  any  vaporisation  whatever  by 
simply  producing  an  atmosphere  containing  inflammable  liquid  in 
extremely  small  particles  distributed  throughout  the  air  in  such 
proportion  as  to  allow  of  complete  combustion.  The  familiar 
explosive  combustion  of  lycopodium,  and  the  disastrous  explosions 
caused  in  the  exhausting  rooms  of  flour  mills  by  the  presence  of 
finely  divided  flour  in  the  air,  have  also  suggested  to  inventors  the 
idea  of  producing  explosions  for  power  purposes  from  combustible 
solids.  Although,  doubtless,  explosions  could  be  produced  in  that 
way,  yet  in  oil  engines  the  production  of  spray  is  only  a  preliminary 
to  the  vaporisation  of  the  oil.  If  a  sample  of  oil  be  sprayed  in 
the  manner  just  described  and  injected  in  a  hot  chamber  also 

filled  with  hot  air,  then  the 
oil  so  sprayed  will  at  once 
pass  into  a  state  of  vapour 
within  that  chamber,  al- 
though the  air  should  be  at 
a  temperature  far  below  the 
boiling  point  of  the  oil. 
The  spray  producer,  in  fact, 
furnishes  a  ready  means  of 
saturating  any  volume  of  air 
with  heavy  petroleum  oil  to 
the  full  extent  possible  from 
the  vapour  tension  of  the  oil 
at  that  particular  tempera- 


FIG.  187.— Perfume  Spray  Producer. 


ture.  The  oil  engines  about  to  be  described  are  in  reality  ex- 
plosion gas  engines  of  the  ordinary  Otto  type  with  special  arrange- 
ments to  enable  them  to  vaporise  the  oil  to  be  used.  The  author 
will,  therefore,  only  describe  such  parts  of  the  engines  as  are 
necessary  to  treat  the  oil  and  to  ignite  it. 

Priestman  Oil  Engine. — Fig.  188  is  a  vertical  section  through 
the  cylinder  and  vaporiser  of  the  Priestman  engine.  Fig.  189 
is  a  section  on  a  larger  scale  showing  the  vaporising  jet  and  the 
air  admission  and  regulation  valve  leading  to  the  vaporiser. 
Fig.  190  is  an  elevation  on  a  smaller  scale  showing  the  general 
arrangement  of  the  engine. 

In  this  engine  oil  is  forced  by  means  of  air  pressure  from  the 


Oil  Engines  4ir 

reservoir  A  through  the  pipe  u  to  the  spraying  nozzle  c,  and  air 
passes  from  the  air  pump  D  by  way  of  the  annular  channel  b  into 
the  sprayer  c,  and  there  meets  the  oil  jet  issuing  from  *,  the  air 
impinges  upon  the  oil,  breaks  it  up  in  spray,  and  the  air  charged 
with  oil  spray  flows  into  the  vaporiser  E,  which  vaporiser  is 
heated  up  in  the  first  place  on  starting  the  engine  by  means  of  a 
lamp  G.  In  the  vaporiser  the  oil  spray  becomes  oil  vapour 
saturating  the  air  within  the  hot  walls,  and  on  the  out-charging 
stroke  of  the  piston  the  mixture  passes  by  way  of  the  inlet  valve 


FIG..  iSS. — Priestman  Oil  Engine  (section  through  vaporiser  and  cylinder). 

H  into  the  cylinder.  The  valve  i  allows  air  to  flow  into  the 
vaporiser  to  displace  its  contents,  and  furnish  air  to  be  further 
saturated  with  oil  spray  and  vapour  for  the  next  stroke.  The 
cylinder  K  is  thus  charged  with  a  mixture  of  air  and  hydrocarbon 
vapour,  some  of  which  may  exist  in  the  form  of  very  fine  spray. 
The  piston  L  then  returns  and  compresses  the  mixture,  and  when 
the  compression  is  quite  complete  an  electric  spark  is  passed 
between  the  points  M  and  a  compression  explosion  is  obtained 
precisely  similar  to  that  obtained  in  the  gas  engine.  The  piston 


4I2 


Oil  Engines 


moves  out  expanding  the  ignited  gases,  and  on  the  return  stroke 
the  exhaust  valve  N  is  opened  and  the  exhaust  gases  are  discharged 
by  way  of  the  pipe  o  round  the  jacket  P  inclosing  the  vaporising 
chamber.  The  vaporising  chamber  is  thus  kept  hot  by  the 
exhaust  gases  whenever  the  engine  starts,  and  it  remains  suffi- 
ciently hot  without  the  use  of  the  lamp  G.  To  obtain  the  electric 
spark  a  bichromate  battery  is  used  and  the  Ruhmkorf  induction 
coil.  The  spark  is  timed  by  contact  pieces  Q  operated  from  the 
eccentric  rod  R  used  to  actuate  the  exhaust  valve  and  the  air 
pump  for  supplying  the  oil  chamber  and  the  spraying  jet.  Fig. 
189  shows  the  spraying  nozzle  on  a  larger  scale.  The  oil  jet 
passes  through  the  small  aperture  a  and  meets  the  air  discharging 


FIG.  189.— Priestman  Oil  Engine  (vaporising  jet  and  air  valve). 

from  the  annulus  b  by  way  of  the  re-entrant  nozzle  c.  Very  fine 
spray  is  produced  in  this  manner. 

To  start  the  engine  the  hand  pump  s  is  operated  to  get  up  a 
sufficient  pressure  to  force  the  oil  through  the  spraying  nozzle, 
and  oil  spray  is  formed  in  the  lamp  G,  and  the  spray  and  air 
mixing  produce  a  blue  flame  which  heats  the  vaporiser.  The 
hand  pump  is  operated  until  the  vaporiser  is  sufficiently  hot  to 
start  the  engine.  The  fly  wheel  is  then  rotated  by  hand,  and  the 
engine  moves  away.  The  eccentric  shaft  is  operated  from  the 
crank  shaft  by  means  of  toothed  wheels  which  reduce  the  speed 
to  one-half  the  revolutions  of  the  crank  shaft.  The  charging 
inlet  valve  is  automatic. 

The  Priestman  engine  was  the  first  engine  capable  of  using 


Oil  Engines 


4^3 


414  Oil  Engines 

heavy  safe  burning  oils.  It  is  somewhat  complex  in  its  con- 
struction, and  suffers  under  what  the  author  considers  the  great 
disadvantage  of  igniting  by  the  electric  spark,  but  it  is  the 
pioneer,  and  the  Messrs.  Priestman  deserve  the  greatest  credit  for 
their  ability  and  pertinacity  in  overcoming  the  formidable  diffi- 
culties in  the  way  of  getting  an  efficient  explosive  mixture  from 
heavy  oils.  Large  numbers  of  the  engines  are  in  operation  and 
appear  to  give  satisfaction.  The  sizes  made  by  Messrs.  Priestman 
vary  from  i  horse  nominal  to  n  horse  nominal,  and  twin  or 
double  cylinder  engines  have  been  made  of  25  horse  nominal. 

In  the  Priestman  engine  governing  is  effected  by  throttling  the 
oil  and  air  supply.  For  this  purpose  the  governor  operates  on 
the  butterfly  valve  T  and  on  the  plug  cock  /  connected  to  it,  by 
means  of  the  spindle  /'.  The  air  and  oil  are  thus  simultaneously 
reduced,  and  the  attempt  is  made  to  maintain  the  charge  entering 
the  cylinder  at  a  constant  proportion  by  weight  of  oil  and  air 
while  reducing  the  total  weight  and  therefore  volume  of  the  charge 
entering.  The  Priestman  engine  therefore  gives  an  explosion  on 
every  second  revolution  under  all  circumstances  whether  the 
engine  be  running  light  or  loaded.  The  compression  pressure  of 
the  mixture  before  ignition  is,  however,  steadily  reduced  as  the 
load  is  reduced,  and  at  very  light  loads  the  engine  is  running 
practically  as  a  non-compression  engine.  This  is  a  grave  dis- 
advantage, as  the  fuel  consumption  per  IHP  rises  rapidly  with  the 
reduction  of  compression. 

Tests  and  Oil  Consumption. — Professor  Unwin  made  a  test  of 
the  Priestman  engine  at  the  Royal  Agricultural  Show  at  Plymouth 
in  1890.  The  engine  tested  was  a  4 7  HP  nominal,  cylinder 
8*5  in.  diameter,  12  in.  stroke,  normal  speed  180  revolutions  per  . 
minute.  The  oil  used  was  that  known  as  Broxbourne  Light- 
house, a  Scotch  paraffin  oil  produced  by  the  destructive  distillation 
of  shale.  Its  density  is  '81  and  flashing  point  about  152°  F. 
The  analysis  of  the  oil  by  Mr.  C.  J.  Wilson  gave  : 

Carbon 86 '01  per  cent. 

Hydrogen          .         .         .         .         .         .         .13-90 

Deficiency -09         „ 

loo'oo  per  cent. 

By  calculation  the  heating  value  is  19,700  thermal  units  F. 


Oil  Engines  415 

per  Ib.  This  is  the  total  heat  evolved  including  heat  of  con- 
densation of  steam  to  the  liquid  state.  The  principal  results 
given  by  the  test  were  as  follows  : 


Indicated  HP 


5^43 


Brake  HP      .         . 4-496 

Duration  of  trial    .         .         .         .         .         .         .         .150  minutes 

Mean  speed  (revolutions  per  minute)     ....  179*5 

Mean  available  pressure  (Ibs.  per  square  inch)       .         .  33  -96 

Explosions  per  minute  .         .         .         .         .         .         .  89*75 

Oil  consumed  per  I  HP  per  hour  (Ibs.)  ....  1*066 

Oil  consumed  per  brake  HP  per  hour  (Ibs.)  .         .         .  *'243 
The  heat  account  is — 

Total  heat  shown  by  indicator 12*67 

Heat  given  to  jacket  water 53 '39 

Exhaust  waste  and  other  losses 33  -96 


In  1892  Professor  Unwin  made  another  trial  of  a  5  HP  Priest- 
man  oil  engine  at  Hull,  in  the  course  of  which  he  used  both 
Russoline  oil  and  Daylight  oil.  The  engine  was  of  the  same 
dimensions  as  the  Plymouth  engine,  that  is  8*5  ins.  cylinder  and 
12  ins.  stroke.  The  volume  swept  by  the  piston  per  stroke  was 
•395  cubic  feet,  and  the  clearance  space  in  the  cylinder  at  the  end 
of  the  stroke  was  "210  cubic  feet.  The  small  air-compressing 
pump  supplying  the  spray  producer  discharged  -033  cubic  feet  per 
stroke.  The  total  weight  of  the  engine  was  36  cwt,  including  a 
fly-wheel  of  10  cwt.  The  principal  results  obtained  were  as 
follows  : 


IHP           '     .       ••.         

Daylight 
o"?6o    . 

Russoline 
7-408 

Brake  HP      .         

7  J    7 

7-722  . 

.          6765 

Mean  speed  (revolutions  per  minute) 

204-33    • 

.      20773 

Mean  available  pressure  (revolutions  per  minute)  . 

53  '2 

.        41-38 

Oil  consumed  per  IHP  per  hour    .... 

•694  Ibs. 

•864  Ibs. 

Oil  consumed  per  brake  HP  per  hour    .         .         . 

•842  „ 

'946    .. 

With  Daylight  oil  the  explosion  pressure  was  151  -4  Ibs.  per 
square  inch  above  atmosphere,  and  with  Russoline  134*3  Ibs. 
The  terminal  pressure  at  the  moment  of  opening  the  exhaust 
valve  with  Daylight  oil  was  35-4  Ibs.,  and  with  Russoline  337  per 
square  inch.  The  compression  pressure  with  Daylight  oil  was 
35  Ibs.,  and  with  Russoline  27-6  Ibs.  pressure  above  atmosphere. 


4i 6  Oil  Engines 

Analyses  were  made  of  the  samples  of  Daylight  and  petroleum 
by  Mr.  C.  J.  Wilson,  F.C.S. 

Daylight  Russoline 

Carbon       .         .         .         84-62  per  cent.     .  .         .         85-88  per  cent. 

Hydrogen.         .         .         i4'86         ,,            .  .         .         i4'oy         ,, 

Oxygen      ...             -52         ,,  -05         ,, 

100 -oo  per  cent.  loo'oo  per  cent. 


Specific  gravity  at  60°  F.    7936    .                                   .     -8226 
Flashing  point     .         .     77°  F 86°  F. 

The  total  heat  of  combustion  of  Daylight  oil  calculates  out  at 
21,490  British  thermal  units,  and  for  Russoline  at  21,180  British 
thermal  units. 

Professor  Unwin  calculates  the  amount  of  heat  accounted  for 
by  the  indicator  as  i8'8  per  cent,  in  the  case  of  Daylight  oil,  and 
15-2  in  the  case  of  Russoline  oil.  Fig.  191  is  a  diagram  taken  by 
Professor  Unwin,  and  published  in  his  paper  read  before  the 
Institution  of  Civil  Engineers  in  1892.  The  largest  diagram 
is  a  full-power  diagram  ;  the  diagram  in  dotted  lines  is  half  power  ; 
and  the  small  light-line  diagram  shows  the  card  given  by  the  engine 
when  working  without  load.  The  various  particulars  of  clearance 
spaces,  maximum  pressure,  pressure  of  compression,  and  stroke 
volume  are  clearly  shown  upon  the  illustration.  From  these  figures 
it  will  be  seen  that  the  Priestman  oil  engine  worked  on  a  con- 
sumption of  '946  Ib.  of  Russoline  oil  per  brake  HP  per  hour,  and 
•842  Ib.  of  Daylight  oil  per  brake  HP  per  hour. 

Professor  Unwin  states  that  the  oil  used  in  starting  the  engine 
was  insignificant  in  quantity,  being  only  about  one  pound  of  oil 
in  each  of  the  two  trials  in  which  it  was  measured. 

The  Samuelson  Oil  Rngine.  —  Messrs.  Samuelson's  engine  is 
constructed  under  the  Griffin  patents,  and  it  resembles  Priestman's 
in  subjecting  the  oil  to  the  preliminary  process  of  spraying  before 
vaporising,  and  in  it  also  the  vaporiser  is  heated  during  the  run- 
ning of  the  engine  by  the  exhaust  gases.  It  differs,  however,  from 
the  Priestman  engine  in  the  methods  of  igniting  and  governing. 
The  tube  igniter  is  used,  and,  instead  of  reducing  the  power  of 
the  explosions  as  is  done  by  Messrs.  Priestman,  the  governing 
device  so  operates  that  when  speed  becomes  too  high,  the  air 
supply  is  entirely  cut  off,  and  the  exhaust  valve  is  also  closed. 


Oil  Engines 


417 


The  exhaust  valve  is  closed  after  the  combustion  products  of 
the  last  explosion  have  been  discharged  from  the  cylinder,  the 
piston  consequently  moves  out,  expanding  the  contents  of  the 
compression  space. 

The  oil  valve  is  simultaneously  shut  off  in  the  sprayer,  so  that 
no  oil  is  injected. 

Fig.  192  is  a  section  of  the  Griffin  patent  oil  sprayer.  The 
air  enters  by  way  of  the  passage  A,  and  discharges  through  the 
nozzle  A',  thereby  creating  a  partial  vacuum  in  the  annular  space 
B  formed  between  the  air  nozzle  and  the  oil  nozzle.  The  passage 


FIG.  191. — Priestman  Oil  Engine  (diagram,  Unwin). 

B2  connects  to  the  oil-supply  chamber  B'  by  way  of  a  spraying  valve 
c  attached  to  a  plunger  stem  c'.  The  air  pressure,  when  admitted, 
forces  down  the  plunger  c',  and  thus  opens  the  valve  c  against  the 
pressure  of  the  spring.  Oil  thus  passes  up  the  passage  B2  from  the 
chamber  B',  and  is  discharged  with  the  air  from  the  nozzle  A'  in  a 
state  of  fine  spray. 

Whenever  the  air  pressure  is  removed  from  the  plunger  c',  the 
spring  forces  the  valve  to  its  seat,  and  cuts  off  the  oil  supply. 
The  air  pressure  is  maintained  at  from  12  to  15  Ibs.  above 

E  E 


Oil  Engines 

atmosphere  by  a  pump  driven  from  an  eccentric  on  the  valve 
shaft. 

The  vaporiser  is  shown  in  longitudinal  transverse  section,  plan 
and  end  elevation  at  fig.  193.  E  is  the  vaporiser,  made  of  cor- 
rugated outline,  and  surrounded  by  the  exhaust  jacket  F.  The 
air  is  admitted  to  the  vaporiser  from  the  atmosphere  by  the 
adjustable  perforated  plate  G,  and  the  spray  nozzle  is  attached 
at  a  point  H,  and  discharges  the  spray  into  the  centre  of  the 
vaporiser. 


US 

FIG.  192.  —  Samuelson  (Griffin)  Oil  Sprayer. 

So  far  the  arrangements  closely  resemble  those  of  the  Priestman 
engine  ;  but,  instead  of  using  the  electric  spark  for  igniting,  the 
incandescent  tube  is  adopted,  and  an  incandescent  metal  tube  is 
heated  and  kept  hot  by  an  ingenious  lamp  shown  at  fig.  194.  In 
this  lamp  oil  is  admitted  to  the  chamber  j  by  the  pipe  K,  and  it  is 
maintained  at  a  constant  level  there  by  means  of  the  overflow  pipe  L. 
A  short  piece  of  wire  M  is  immersed  in  the  oil,  and  the  oil  runs  up 
the  wire  and  covers  the  bent  part  by  reason  of  capillary  attraction. 
Air  under  pressure  is  admitted  by  way  of  the  pipe  N  adjusted  by 


Oil  Engines  419 

the  screw  N',  and  it  passes  to  the  nozzle  o,  striking  upon  the  bent 
part  of  the  wire  M.     The  air  thus  blows  the  oil  off  the  wire,  and 


FIG.  193.  —  Satnuelson  Engine  Vaporiser. 

at  the  same  time  the  jet  sucks  in  a  further  supply  of  air  through 
holes  P,  and  the  mixed  air  and  oil  spray  pass  through  the  tube  Q 
to  the  asbestos-lined  funnel  R  ;  on  igniting  the  mixture  within  this 


FIG.  194. — Samuelson  Engine  Spray  Lamp. 

funnel,  it  burns  with  a  fierce  blue  flame,  and  heats  up  the  igniter 
tube  s  ;  this  tube  opens  into  the  engine  cylinder,  and  ignites  the 
mixture  when  it  is  compressed.  To  start  the  engine,  the  air  pump 

E  E  2 


420  Oil  Engines 

is  worked  by  hand  until  the  required  pressure  is  obtained  ;  air  is 
then  turned  on  the  sprayer,  and  the  spray  lighted.  By  this  means 
the  vaporiser  is  heated  for  about  ten  minutes  from  within,  the 
burned  gases  being  discharged  through  a  special  valve  opening 
into  the  exhaust,  which  valve  is  closed  when  sufficient  heat  is 
attained,  The  heating  lamp  of  the  incandescent  tube  is  in  the 
meantime  lighted,  and  the  engine  is  ready  to  start. 

No  independent  tests  have  been  made  of  the  power  and  oil 
consumption  of  this  engine  within  the  author's  knowledge. 

Engines  in  which  the  Oil  is  injected  into  the  Cylinder  and 
vaporised  within  the  Cylinder. — The  engines  at  present-  in  use  in 
Britain  falling  under  this  head  are  those  manufactured  and  sold 
by  Messrs.  Hornsby  of  Grantham,  Messrs.  Robey  of  Lincoln,  and 
a  German  engine  known  as  the  '  Capitaine.'  Messrs.  Hornsby 
term  their  engine  the  Hornsby-Ackroyd  engine,  and  it  is  un- 
doubtedly the  most  successful  and  simple  of  this  type. 

Hornsby-Ackroyd  Oil  Engine. — Fig.  195  is  a  section  through 
the  vaporiser  and  cylinder  of  the  Hornsby-Ackroyd  engine,  and 
fig.  196  shows  the  inlet  and  exhaust  valves  also  in  section  placed 
in  front  of  the  vaporiser  and  cylinder  section.  The  main  idea  of 
this  engine  is  simple  in  the  extreme.  Vaporising  is  conducted 
in  the  interior  of  the  combustion  chamber,  which  chamber  is  so 
arranged  that  the  heat  of  each  explosion  maintains  it  at  a  tem- 
perature sufficiently  high  to  enable  the  oil  to  be  vaporised  by 
mere  injection  upon  the  hot  surfaces,  the  heat  being  also  sufficient 
to  cause  the  ignition  of  the  mixture  of  vapour  and  air  when  com- 
pression is  completed.  The  vaporiser  A  is  heated  up  by  a 
separate  lamp,  the  oil  is  injected  at  the  oil  inlet  B,  and  the  engine  is 
rotated  by  hand.  The  piston  then  takes  in  a  charge  of  air  by  the 
air  inlet  valve  into  the  cylinder,  the  air  passing  by  the  port  directly 
into  the  cylinder  without  passing  through  the  vaporiser  chamber. 
While  the  piston  is  moving  forward  taking  in  the  charge  of  air  the 
oil  which  has  been  thrown  into  the  vaporiser  is  vaporising  and 
diffusing  itself  through  the  vaporising  chamber,  mixing,  however, 
only  with  the  hot  products  of  combustion  left  by  the  preceding 
explosion.  During  the  charging  stroke  the  air  enters  through  the 
cylinder,  and  the  vapour  formed  from  the  oil  is  almost  entirely 
confined  to  the  combustion  chamber.  On  the  return  stroke  of 


Oil  Engines 


421 


the  piston  air  is  forced  through  the  somewhat  narrow  neck  a  inta 
the  combustion  chamber,  and  it  there  mixes  with  the  vapour  con- 
tained in  it.  At  first,  however,  the  mixture  is  too  rich  in  inflammable 


FIG.  195.  —  Hornsby-Ackroyd  Engine 
(section   through    vaporiser   and    cylinder). 

vapour  to  be  capable  of  ignition.  As  the  compression  proceeds, 
however,  more  and  more  air  is  forced  into  the  vaporiser  chamber, 
and  just  as  the  compression  is  completed  the  mixture  attains 


FIG.  196 Hornsby-Ackroyd  Engine 

(section  through  valves,  vaporiser,  and  cylinder). 

proper  explosive  proportions.  The  sides  of  the  chamber  are 
sufficiently  hot  to  cause  explosion,  and  the  piston  moves  forward 
under  the  pressure  of  the  explosion  so  produced. 

As  the  vaporiser  A  is  not  water -jacketed,  and  is  connected  to 


422 


Oil  Engines 


the  metal  of  the  back  covej  only  by  the  small  sectional  area  of  cast 
iron  forming  the  metal  neck  a,  the  heat  given  to  the  surface  by 
each  explosion  is  sufficient  to  raise  its  temperature  to  about 
700-800°  C.  and  keep  it  there. 

It  is  a  peculiar  fact  that  oil  vapour  mixed  with  air  will  explode 
by  contact  with  a  metal  surface  at  a  comparatively  low  tempera- 
ture, and  this  accounts  for  the  explosion  of  the  compressed 
mixture  in  the  combustion  chamber  A,  which  is  never  really  raised 
to  a  red  heat.  It  has  long  been  known  to  engineers  conversant 
with  gas  engines  that  under  certain  conditions  of  internal  surfaces 
a  gas  engine  may  be  made  to  run  and  ignite  with  very  great 
regularity  without  incandescent  tube  or  any  other  form  of  igniter, 


FIG.  197.— Cylinder  Ignitions,  Otto  Engine. 

if  some  portion  of  the  interior  surfaces  of  the  cylinder  or  combus- 
tion space  be  so  arranged  that  the  temperature  can  rise  moderately ; 
then,  although  that  temperature  may  be  too  low  to  ignite  the 
mixture  at  atmospheric  pressure,  yet  when  compression  is  com- 
plete the  mixture  will  often  ignite  in  a  perfectly  regular  manner. 
Fig.  197  shows  a  series  of  diagrams  taken  from  the  ordinary  Otto 
engine  igniting  in  this  manner  without  any  special  igniter,  and  it 
will  be  observed  that  the  diagrams  are  very  fairly  regular.  The 
author  has  noticed  this  peculiar  fact  in  connection  with  one  of 
his  old  engines  described  on  page  184.  He  placed  a  stud  A, 
fig.  198,  in  the  end  of  the  piston  B  ;  this  stud  was  sufficiently  long 
to  project  the  head  well  into  the  explosive  mixture ;  on  starting 


Oil  Engines 


423 


the  engine  with  the  ordinary  flame-igniting  valve  and  running  it 
for  1 5  minutes  in  the  usual  way,  it  was  found  that  the  flame- 
igniting  arrangement  could  be  entirely  stopped  from  action  and 
the  engine  run  regularly,  the  mixture  igniting  only  because  of  the 
incandescent  head  of  the  bolt  A,  which  projected  into  the  explosive 
mixture  after  compression  and  ignited  only  when  the  mixture  was 
fully  compressed.  In  this  arrangement,  however,  the  bolt  A  was 
found  to  attain  a  high  red  heat. 

It  is  a  curious  and  interesting  fact  that  with  heavy  oils  ignition 
is  more  easily  accomplished  at  a  low  temperature  than  with  light 
oils.  The  explanation  seems  to  be  that  in  the  case  of  light  oils 
the  hydrocarbon  vapours  formed  are  tolerably  stable  from  a 
chemical  point  of  view,  but  the  heavy  oils  very  easily  decompose 
by  heat  and  separate  out 
their  carbon,  liberating  the 
combined  hydrogen,  and  at 
the  moment  of  liberation 
the  hydrogen  being  in  what 
chemists  know  as  the  nas- 
cent state  very  readily  enters 
into  combination  with  the 
oxygen  beside  it.  In  this 
manner  combustion  is  more 
easily  started  with  a  heavy  FIG.  198. -Clerk  Engine  with  bolt  igniter. 

oil  than  with  a  light  one. 

Messrs.  Hornsby's  vaporiser  is  of  D  shape,  the  rounded  part 
above  and  the  straight  part  of  the  D  below. 

To  start  the  engine  the  vaporiser  is  heated  by  a  separate 
heating  lamp,  which  lamp  is  supplied  with  an  air  blast  by  means 
of  a  hand-operated  fan.  This  operation  should  take  about  nine 
minutes.  The  engine  is  then  moved  round  by  hand,  and  starts  in 
the  usual  manned  The  oil  tank  is  placed  in  the  bedplate  of  the 
engine.  The  air  and  exhaust  valves  are  driven  by  cams  on  a  valve 
shaft. 

Figure  199  is  a  general  view  of  the  external  appearance  of  the 
engine,  from  which  it  will  be  seen  that  the  governing  is  effected 
by  a  centrifugal  governor.  This  governor  operates  a  bye  pass 
valve,  which  opens  when  the  speed  is  too  high  and  causes  the  oil 


424  Oil  Engines 

pump  to  return  the  oil  to  the  oil  tank.     The  fan  and  starling  lamp 
will  be  seen  in  the  lower  part  of  the  illustration. 

Tests  and  Oil  Consumption. — Messrs.  Hornsby's  engine  was 
exhibited  at  the  Royal  Agricultural  Show  at  Cambridge,  and  after 
an  exhaustive  test  by  the  judges  of  the  show  in  competition  with 
engines  by  nine  other  makers,  the  Hornsby  engine  was  awarded 
the  first  prize  of  5o/.  The  engine  tested  was  given  as  of  8  brake 
HP,  and  its  dimensions  were — diameter  of  cylinder  10  in., 
stroke  15  in.,  weight  of  engine  40  cwt.  During  the  trials, 
according  to  Professor  Capper's  report,  the  engine  ran  without 


I 


FIG.  199.— Hornsby- Ackroyd  Oil  Engine. 


hitch  of  any  kind  from  start  to  finish.  Its  action  was  faultless. 
One  attendant  only  was  employed  all  through  the  trials,  and 
started  the  engine  easily  and  with  certainty  after  working  the  hand 
blast  to  the  lamp  for  8  minutes.  During  three  days'  run  the 
longest  time  taken  to  start  was  9  minutes,  and  the  shortest 
7  minutes.  When  the  engine  stopped  each  day  the  bearings 
were  cool  and  the  piston  was  moist  and  well  lubricated  ;  the 
revolutions  were  very  constant,  and  the  power  developed  did  not 
vary  one  quarter  of  a  brake  HP  from  day  to  day.  The  oil 
consumed,  reckoned  on  the  average  of  the  three  days'  run,  was 
•919  Ibs.  per  brake  HP  per  hour.  The  oil  used  was  Russoline, 


OH  Engines  425 

sold  in  Cambridge  at  that  time  at  the  price  of  $\d.  per  gallon. 
At  this  rate  the  cost  for  oil  per  brake  HP  was  \d.,  and  this 
included  all  the  oil  used  for  the  starting  lamp. 

Mr.  C.  F.  Wilson,  F.C.S.,  has  made  an  analysis  of  the 
Russoline  oil  used  for  the  purpose  of  testing  the  oil  engines 
exhibited  at  Cambridge,  and  found  that  the  specific  gravity  at 
60°  F.  -824,  the  flashing  point  (Abel  test)  88°  F.,  the  total  heat  of 
combustion  was  11*055  calories,  but  after  deducting  for  the  heat 
due  to  the  condensation  of  water  vapour  this  reduced  to  10-313 
calories.  The  oil  contained  14-05  per  cent,  hydrogen.  Mr. 
Wilson  makes  the  observation  that  this  oil  appears  to  be  very 
constant  in  composition,  because  a  similar  oil  examined  by  him  a 
year  before  gave  14'oy  per  cent,  hydrogen,  and  a  corrected 
calorific  value  of  10-3  calories,  so  that  the  two  samples  supplied 
at  an  interval  of  a  year  were  practically  constant  in  com- 
position. 

The  mean  power  exerted  during  the  three  days'  trials  was 
8-35  brake  horse.  At  a  subsequent  full-power  trial  of  the  same 
engine  at  the  show,  a  brake  HP  of  8-57  was  obtained,  the 
engine  running  at  a  mean  speed  of  239-66  revolutions  -  per 
minute  and  the  test  lasting  for  two  hours  ;  the  indicated  power 
was  10-3  horse,  the  explosions  per  minute  119:83,  the  mean 
effective  pressure  28-9  pounds  per  square  in.,  the  oil  used  per 
IHP  per  hour  was  -81  and  per  brake  HP  per  hour  -977  pounds. 
According  to  Professor  Capper  the  heat  account  of  the  engine 
was  : 

Heat  shown  on  indicator  diagram  IHP   .         .         .       16-9  per  cent. 

Heat  rejected  in  jackets 29-5 

Heat  rejected  in  exhaust  and  other  losses         .         .       53-6 


In  these  tests,  however,  Professor  Capper  erroneously  takes 
the  corrected  heat  value  of  the  oil  instead  of  the  total  heat  value. 
In  determining  the  absolute  efficiency  of  any  engine,  it  is  neces- 
sary to  take  as  a  basis  the  total  amount  of  heat  evolved  by  the 
combustion  from  the  atmospheric  temperature  to  the  atmospheric 
temperature  again.  The  author  has  recalculated  these  figures,  and 
finds  the  correct  heat  account  below  : 


426  Oil  Engines 

Heat  shown  on  indicator  diagrams  per  IHP 
Heat  rejected  in  jackets    .... 
Heat  rejected  in  exhaust  and  other  losses 


15-3  per  cent. 

26-8 

57'9 


In  a  test  of  this  engine  made  at  the  same  time  but 
half-power,  the  brake  HP  developed  was  4-57  at  235-9  revolu- 
tions per  minute,  and  the  oil  used  per  brake  HP  per  hour  was 
1-49  pounds.  On  a  four  hours'  test  with  this  engine  running 
entirely  without  load  at  240  revolutions  per  minute  it  was  found 
that  it  consumed  4-23  pounds  of  oil  per  hour.  Fig.  200  is  a  card 


Jbs.  per  sq. 

absolute 

/*> 
120 

too 
80 
60 
40 
20 

0 

in. 

r\ 

\ 

\ 

»v 

\ 

x 

x 

^ 

*^, 

**s, 

^ 

•^  — 

^^. 

*^ 

^ 

/         -2          '3         •+          3       '6         -7          8  9         t-0      /•/  cb.  ft. 

Brake  HP,  8'5j  ;  indicated  HP,  10*3;  diam.  of  cylinder,  10" ;  stroke,  15";  revs. 
per  min.  2jq'66  ;  explosions  per  min.  ug'8^  ;  mean  pressure,  28*9  Ibs.  per  sq.  in.  ; 
pressure  ol  explosion,  112  ,bs.  per  sq.  in.  above  atmos.  ;  pressure  of  compression, 
50  Ibs.  ;  oil  per  IHP  hour,  '81  Ibs.  ;  oil  per  BHP  hour,  "977  Ibs. 

FIG.  200 — Hornr.by-Ackroyd  Oil  Engine  (diagram). 
Average  card,  two  hours'  full  power  trial.     Russoline  oil. 

from  the  Hornsby  engine,  being  an  average  card  of  the  two  hours' 
full-power  trial.  The  cylinder  volume  is  given  in  cb.  ft.  and  the 
compression  space  is  also  given.  From  this  diagram  it  will.be 
observed  that  the  average  pressure,  the  maximum  pressure  and 
the  pressure  of  compression  are  very  low,  and  that  consequently  a 
large  cylinder  is  required  to  develop  a  given  power,  while  it  is 
worth  observing  how  beautifully  regular  is  the  ignition  obtained  by 
the  simple  device  of  firing  from  the  surfaces  of  the  hot  combustion 
chamber. 

Robey  Oil  Engine. — The  Robey  oil  engine  is  constructed  in 


Oil  Engines 


427 


accordance  with  the  patents  of  Messrs.  Richardson  and  Norris 
and  it  very  closely  resembles  the  Hornsby-Ackroyd  engine. 
Like  the  Hornsby  engine,  it  depends  upon  the  heat  of  the 
combustion  space  walls  both  for  vaporising  and  igniting,  and 
the  governing  is  effected  by  diminishing  the  oil  supply.  It 
differs,  however,  from  the  Hornsby  engine  in  this,  that  the  com- 
bustion chamber  is  made  with  a  water  jacket,  and  an  inner 
lining  is  inserted  from  behind,  which  lining  stands  clear  of  the 
water-jacketed  part  and  becomes  hot  by  the  explosion.  Fig.  201 
is  a  section  showing  one  arrangement  of  the  combustion  chamber 
of  the  Robey  engine.  The 
liner  A  is  introduced  into 
the  combustion  chamber 
from  behind,  and  it  is  easily 
removed  when  it  is  desired 
to  clean  or  repair.  The 
engine  also  differs,  it  will  be 
observed,  in  the  position  of 
the  inlet  and  exhaust  valves. 
The  charge,  instead  of  pass- 
ing directly  into  the  cylinder 
as  in  the  Hornsby  engine, 
passes  first  outside  the  com- 
bustion space  into  the  cylin- 
der. The  author  is  unaware 
of  any  official  test  of  this 

engine,  but  fig.  202  is  a  diagram  taken  by  him  from  a  Robey  oil 
engine  of  6  in.  cylinder  and  9  in.  stroke  running  at  260  revolu- 
tions per  minute,  and  using  American  oil  having  a  specific  gravity 
of  '857  at  50°  F.  The  diagrams  from  Messrs.  Hornsby's  and 
Robey's  engines  prove  that  this  system  of  ignition  and  vaporising 
supplies  a  very  regular  and  effective  ignition. 

Capitaine  Oil  Engine. — The  Capitaine  oil  engine  resembles 
the  Robey  engine  in  surrounding  the  water  chamber  with  a  water 
jacket,  and  in  introducing  an  internal  liner  kept  clear  of  the  water- 
jacketed  sides  to  give  sufficient  heat  for  the  purpose  of  vaporising 
and  igniting.  An  engine  of  this  type  was  entered  for  trial  at  the 
Royal  Agricultural  Show  at  Plymouth,  and  it  was  declared  at 


FIG.  20 1.  —  Robey  Oil  Engine 
(section  through  combustion  space). 


428 


Oil  Engines 


5  brake  HP,  cylinder  7]-  in.  diameter,  stroke  ;i  in.,  speed  300 
revolutions  per  minute,  weight  17  cwts.  The  engine  was  designed 
to  use  Tea  Rose  oil,  and  the  adjustments  were  found  to  be  un- 
suitable for  the  use  of  Russoline  oil,  which  was  the  oil  settled  by 
the  judges  for  use  during  competition.  The  engine  was  therefore 
withdrawn  from  the  competition,  and  the  author  is  unaware  of 
any  official  tests.  In  his  report,  however,  Professor  Capper  says 
that  using  Tea  Rose  oil  the  engine  runs  at  300  revolutions  per 
minute  and  develops  4^  brake  HP,  starting  from  the  moment 
of  heating  the  vaporiser  in  about  five  to  ten  minutes.  Fig.  203 
is  a  section  through  the  vaporiser  and  combustion  chamber.  A 
is  the  inlet  valve  operating  automatically.  It  contains  a  central 


ibs  pe-r  Sy  in 


FIG.  2C2. — Robey  Oil  Engine  (diagram,  Clerk). 


spindle  B,  having  at  the  point  of  it  a  valve  seat  b.  The  valve  A 
has  thus  two  seats,  one  the  usual  external  seat  and  the  other  an 
internal  seat,  closing  on  its  valve  seat  b.  The  spindle  B  operates 
within  a  hollow,  having  a  hole  c  opposing  the  oil  supply  pipe  D. 
E  is  the  vaporiser,  which  is  surrounded  by  a  non-conducting 
casing  F,  which  in  turn  is  inclosed  in  a  metal  casing  G  within  the 
combustion  space  H.  i  is  the  water  jacket. 

To  start  the  engine  the  vaporiser  is  heated  by  a  hand  spirit 
lamp.  This  operation  takes  from  five  to  ten  minutes,  and  according 
to  Professor  Capper  the  engine  then  starts  away  very  easily.  On  the 
suction  stroke  the  air  inlet  valve  opens,  thereby  opening  also  the 


Oil  Engines 


429 


internal  valve,  and  air  passes  into  the  cylinder,  mostly  passing  round 
outside  the  casing.  A  portion,  however,  passes  through  the  centre  of 
the  valve,  and  with  it  enters  the  oil  from  the  pipe  D.  A  small  quantity 
of  oil  and  air  thus  passes  through  the  centre  of  the  vaporiser  E> 
and  the  vapour  enters  the  cylinder  to  form  mixture  for  explosion. 
Upon  compression  the  compressed  mixture  ignites  at  the  internal 
hot  surfaces  of  the  vaporiser  E. 

The  vaporiser  E,  with  its  non-conducting  material  F  and 
outer  casing  G,  is  all  immersed  in  the  flame  of  the  explosion  ;  but 
the  vaporiser  E  becomes  hottest  because  it  is  not  subject  to  the 
cooling  action  of  the  air  supply,  which  mostly  passes  round  be- 
tween the  casing  F  and  the 
combustion  chamber.  Only 
a  small  portion  of  air  passes 
through  the  hole  c  with  the 
oil  entering  the  pipe  D  ;  the 
surface  G  also  radiates  more 
heat  to  the  cold  walls,  so  that 
the  vaporiser  is  kept  at  the 
highest  temperature  by  the 
repeated  explosions. 

The  oil  pump  used  in  the 
Capitaine  engine  is  of  peculiar 
construction.  Fig.  204  is  a 
section.  The  plunger  A  is 
operated  by  bell  crank  lever, 
roller  and  cam,  actuated  in 
the  usual  way ;  and  a  slide 
valve  B  is  actuated  also  by 

lever  c  and  cam  D  ;  the  plunger  is  packed  by  leather  packing, 
and  operates  in  a  glycerine  bath  F.  Oil  G  floats  on  the  top  of 
the  glycerine  bath,  and  is  discharged  through  the  slide  valve  B. 
In  this  way  the  plunger  A  is  caused  to  operate  in  a  space  of  ample 
capacity. 

Engines  in  which  the  Oil  is  vaporised  in  a  Device  external  to  the 
Cylinder,  and  introduced  into  the  Cylinder  in  the  state  of  Vapour  — 
Engines  falling  under  this  class  are  manufactured  by  Messrs. 
Crossley,  Tangyes,  Fielding  &  Platt,  Campbell  Gas  Engine  Co., 


FIG.  203.  —  Capitaine  Oil  Engine 
(section  through  vaporiser). 


430 


Oil  Engines 


Ltd.,  the  Britannia   Co.,  Clarke,  Chapman  &  Co.,    Weyman  & 
Hitchcock,  and  Wells  Bros. 

Crossley  Brothers'  Oil  Engine. — Fig.  205  shows  the  general 
appearance  of  Messrs.  Crossley's  oil  engine.  In  this  engine  a 
separate  vaporiser  is  arranged,  communicating  with  the  cylinder 
by  a  vapour  valve.  The  engine  is  ignited  by  an  incandescent 
tube,  and  both  incandescent  tube  and.  vaporiser  are  heated  by 
the  same  lamp.  The  exhaust  and  air-inlet  valves  are  placed  in 
opposition  to  each  other,  the  air-inlet  valve  being  automatic  and 
above  the  exhaust  valve  ;  both  open  into  the  cylinder  combustion 

space.     The  exhaust  valve 

£}  Q  is  actuated  in  the  ordinary 

manner  from  the  valve 
shaft.  The  governor  is  an 
ordinary  rotating  governor 
of  the  hit-and-miss  type, 
or  in  the  small  engines 
an  inertia  governor,  and 
when  the  speed  is  exces- 
sive a  link  is  intercepted 
which  ordinarily  opens  the 
vapour  valve,  and  the  valve 
remains  closed.  No  charge 
is  then  admitted  to  the 
cylinder.  The  vapour  valve 
upon  opening  allows  the 
suction  of  the  piston  to 
draw  in  a  charge  of  oil  to 


FIG.  204.— Capitaine  Oil  Engine 
(section  through  oil  pump). 


the  vaporiser,  and  oil,  vapour  and  air  from  the  vaporiser  to  the 
cylinder.  The  charge  admitted  to  the  vaporiser  is  thus  heated 
during  the  period  of  an  entire  forward  stroke.  The  air-inlet  valve 
is  opened  by  the  vacuum  caused  by  the  piston,  and  part  of  the 
air,  on  its  way  to  the  cylinder,  passes  first  through  a  heated  coil, 
and  then  through  the  vaporiser.  The  heated  air  charge  thus 
carries  off  the  oil  vapour  through  the  vapour  valve. 

Messrs.  Crossley  have  used  several  lamps  for  the  purpose  of 
heating,  but  the  type  of  lamp  now  used  by  them,  and  indeed  by 
many  others,  is  that  best  explained  by  a  description  of  a  small 


Oil  Engines 

lamp  sold  as  the  Etna  lamp.     This  lamp  is  shown  in  section  and 
plan  at  fig.  206,  and  its  action  and  construction  are  as  follows  : 

The  lamp  comprises  a  stout  brass  oil-  and  air-containing  vessel 
A,  having  fitted  in  it  a  small  air  pump  B.  This  pump  projects 
within  the  vessel  A,  and  has  at  its  lower  end  a  pump  valve  opening 
inwards,  which  allows  the  air  to  pass  from  the  pump  into  the 
vessel,  but  prevents  it  leaking  back  into  the  pump.  The  pump 
leathers  cup  downwards,  to  close  tight  when  the  air  is  compressed  ; 
but  when  the  piston  is  withdrawn  the  air  passes  the  leathers  ori 


FIG.  205.  — Crossley  Oil  Engine. 

the  up-stroke,  so  that  no  second  valve  is  required.  The  piston 
leathers  act  as  a  valve  in  the  manner  so  well  known  in  connection 
with  pneumatic  tyre  inflating  pumps.  The  vessel  A  has  also  an 
oil  filter  c,  an  air-relief  pin  D,  and  above  it  carries  the  lamp  proper, 
consisting  of  a  continuous  arrangement  of  tubes  and  passages, 
E,  F,  G,  H,  which  communicate  with  the  oil  in  the  vessel  A  by  the 
pipe  E,  which  dips  to  nearly  the  bottom  of  the  vessel.  The  tube 
E  leads  from  the  oil  vessel  to  the  square  coil  F,  seen  more  clearly 
in  dotted  lines  on  the  plan.  The  tube  G  leads  from  F  into  a  pas- 
sage shown  in  the  casting  H.  The  casting  is  drilled  out  to  carry  a 


432  Oil  Engines 

fine  nozzle  piece  i,  fitted  on  as  shown.     A  hood  or  sleeve  j  is 
slipped  over  the  whole  tube  arrangement.     The  sleeve  has  two  large 


FIG.  206.— Etna  Lamp. 

air  inlet  holes  K,  one  of  which  is  clearly  seen  in  the  section.  Smaller 
holes  are  made  in  the  sleeve  opposite  the  square  tube  piece  F. 


Oil  Engines  433 

To  start  the  lamp,  the  vessel  A  is  partly  filled  with  petroleum 
by  way  of  the  oil  cup  c,  the  cap  is  screwed  on,  and  the  saucer- 
shaped  depression  in  the  top  of  the  vessel  A  is  filled  with  spirit 
and  ignited.  The  flame  produced  heats  up  the  tube  arrangement 
and  the  funnel  or  hood.  About  one  minute  suffices  to  heat  it  to 
a  high  enough  temperature  for  starting.  The  air  pump  B  is  now 
operated,  and  air  is  forced  into  the  vessel  A  under  pressure,  and 
it  presses  upon  the  surface  of  the  oil  and  forces  it  up  the  tube  E. 
It  rises  in  the  tube  till  it  reaches  the  hot  part,  when  the  oil  is 
caused  to  boil  and  vapour  is  generated  ;  this  vapour  issues  at  the 
small  jet  i,  and  as  this  jet  is  small  the  pressure  rises.  The  vapour 
jet  ignites  at  the  external  flame,  and  a  powerful  flame  shoots  into 
the  hood  j,  and  by  its  motion  sucks  in  a  charge  of  air  by  way 
of  the  slots.  The  flame  leaving  the  hood  j  is  thus  mixed 
with  air,  and  a  powerful  blue  smokeless  flame  leaves  the  hood, 
which  flame  is  capable  of  heating  up  metal  surfaces  to  incan- 
descence without  depositing  soot.  The  flame  plays  on  the  tubes 
E,  F,  G,  and  so  supplies  heat  to  the  oil.  A  small  pressure  of  air  is 
required,  and  if  excess  has  been  pumped  in,  it  is  discharged  by 
the  plug  D. 

If  too  great  an  air  pressure  be  given,  the  air  will  force  the  oil 
up  to  the  jet  I,  but  with  the  correct  pressure  the  air  just  keeps  the 
oil  high  enough  in  the  tube  E  to  generate  sufficient  vapour.  Pegs 
are  arranged  to  allow  the  tubes  to  be  cleaned.  A  few  strokes  of 
the  air  pump,  supply  air  sufficient  to  operate  the  lamp  for 
hours. 

Fig.  207  shows  a  vertical  section  and  a  sectional  plan  of  the 
Crossley  vaporiser  and  incandescent  tube.  The  sectional  plan  is 
taken  on  the  line  x  Y  of  the  vertical  section,  through  the  vapour 
admission  and  igniting  port  of  the  engine,  and  the  sectioned  metal 
is  part  of  the  back  cover  or  end  of  the  combustion  chamber.  The 
combustion  chamber  is  thoroughly  water-jacketed  like  the  rest  of 
the  engine.  When  the  suction  stroke  of  the  engine  begins,  the 
vapour  valve  G  is  opened  by  the  bell  crank  lever,  operated  from 
the  valve  shaft  by  a  link.  This  link  is  controlled  by  the 
governor  so  as  to  either  hit  or  miss  the  cam  by  a  knife-edge 
contrivance.  While  the  engine  is  at  work,  therefore,  the  valve  G  is 
either  entirely  opened  or  entirely  closed  on  the  charging  stroke, 

F  F 


434 


Oil  Engines 


and  the  governing  is  the  same  as  the  usual  gas  engine  governing. 
When  the  valve  G  is  opened  considerable  suction  to  the  engine 
cylinder  is  caused,  as  the  air  inlet  valve  to  the  cylinder  is 
automatic,  and  is  held  to  its  seat  by  a  spring.  The  vaporiser 
passages  communicate  with  the  vapour  valve  G,  and  a  small 
quantity  of  heated  air  passes  over  the  oil  and  carries  off  the 
vapour.  The  vaporiser  is  heated  by  the  lamp,  and  the  products 


JC- 


FIG.  207. — Crossley  Vaporiser. 

of  combustion  are  discharged  by  the  funnel  D.  Fig.  207  shows 
this  very  clearly.  The  lamp  produces  a  powerful  Bunsen  flame, 
which  first  heats  up  the  igniter  c  to  incandescence,  then  it  plays 
on  the  vaporiser  having  drilled  holes  B  B  B  B,  and  the  gases  pass 
up  the  funnel.  A  casing  surrounds  the  heated  parts. 

The  funnel  has  an  air  space  E  surrounding  it,  which  is  divided 
up  by  louvre  projections.  Small  holes  F  open  to  the  air  at  the 
top.  When  the  vapour  valve  G  is  opened,  air  is  drawn  in  by  the 


j:  Oil  Engines,  435 

holes  F,  passes  down  the  air  space  E,  guided  from  side  to  side  by 
the  baffle  or  louvre  projections  ;  the  air  current  reaches  the  passage 
B  and  passes  into  the  vaporiser,  above  the  oil  pipe  or  channel 
A.  The  air  there  meets  the  liquid  oil,  also  sucked  in  by  the 
partial  vacuum,  and  the  hot  air  carries  the  oil  through  the 
vaporiser  along  the  passage  B,  down  along  a  similar  passage 
under  it,  and  along  B  to  the  vapour  valve  G.  The  oil  is  thus 
thoroughly  vaporised  and  carried  away  by  the  hot  air  current. 
One  important  point  to  insure  effective  vaporisation  is  to  heat 
the  air  thoroughly,  and  reduce  its  quantity  as  much  as  possible. 
This  is  done  by  limiting  the  dimensions  of  the  openings  F.  The 
air  and  oil  vapour  pass  by  the  valve  G  and  admission  port  to  the 


FIG.  208.— Crossley  Oil  Measurer. 

engine  cylinder,  and  there  mix  with  the  air  entering  by  the 
automatic  air  inlet  valve  at  the  top  of  the  cylinder  ;  the  mixture  is 
then  compressed  and  ignited  when  compression  is  completed  by  a 
timing  valve  of  the  ordinary  Crossley  type  connected  to  the 
igniting  tube  c.  The  igniting  tube  c  communicates  with  the  ad- 
mission passage  by  a  small  hole  on  the  under  side  passing  through 
the  casting  of  the  vaporiser.  The  tube  c  is  surrounded  by  a  cast- 
iron  protecting  tube  to  prevent  too  rapid  oxidation. 

The  incandescent  tube  c  has  at  its  outer  end  an  inlet  suction 
valve,  which  opens  inward  at  each  suction  stroke,  and  thoroughly 
clears  out  the  burned  gases  of  the  last  explosion,  and  so  insures 
certain  explosion  when  the  compressed  mixture  is  admitted. 

The  oil  supplying  and  measuring  arrangements  are  very  perfect. 

F  F  2 


436  Oil  Engines 

The  pump  does  not  measure  the  oil,  but  only  supplies  it  in  ex- 
cess to  a  very  simple  measuring  device.  Fig.  208  is  a  diagrammatic 
section  of  that  device.  The  hole  a  is  the  oil-measuring  aperture, 
and  it  opens  to  the  small  lift  valve  b,  which  communicates  with 
the  pipe  A,  fig.  207  ;  oil  is  spirted  from  the  end  of  the  pipe  c  by 
the  pump,  and  it  fills  the  hole  a  up  to  the  top  ;  the  excess  oil 
drains  away  to  the  chamber  d  and  returns  by  the  pipe  e  to  the 
reservoir  in  the  tank  in  the  base  of  the  engine.  When  the 
opening  of  the  vapour  valve  causes  suction  in  the  vaporiser,  the 
valve  b  lifts,  and  the  oil  charge  contained  in  the  hole  a  is  sucked 
in,  air  following  it  to  clear  it  all  out  into  the  vaporiser.  By  this 
device  a  constant  volume  of  oil  is  measured  into  the  vaporiser  for 
each  working  stroke  of  the  engine,  and  this  measurement  is 
accurate  and  unvarying,  even  when  the  speed  of  the  engine 
changes. 

The  oil  pump  is  large  enough  to  discharge  a  considerable 
excess  of  oil,  and  one  pump  plunger  serves  both  for  vaporiser  and 
lamp.  The  pump  discharges  through  two  lift  valves,  one  of 
which  is  loaded  by  a  spring  to  lift  at  about  20  Ibs.  per  sq.  in.,  and 
the  other  is  not  loaded  but  lifts  freely.  The  loaded  valve  dis- 
charges to  the  vaporiser  oil  measurer,  and  the  free  valve  discharges 
to  the  lamp. 

The  lamp  operates  on  the  principle  of  the  Etna  lamp,  but 
instead  of  a  coil,  a  gun-metal  chamber  is  used,  having  a  central 
aperture  for  flame,  a  jet  of  small  diameter  at  the  foot  of  the 
central  aperture,  and  a  pipe  leading  to  the  connected  space  from 
the  oil  pump.  The  jet  is  very  fine,  and  as  the  oil  finds  its  way  into 
the  chamber,  vapour  is  formed  which  issues  from  the  jet  and 
forms  with  air  a  Bunsen  flame  which  heats  up  the  lamp  chamber, 
and  heats  to  incandescence  the  igniting  tube  as  well  as  the 
vaporiser  and  air  heater.  The  lamp  is  started  in  the  usual 
manner  by  heating  with  flame  from  some  oil-soaked  rag  or  waste  ; 
this  is  done  to  avoid  the  use  of  any  light  oils  for  starting. 

It  is  found  by  experience  that  the  vapour  jet  hole  should  be 
small  enough  to  generate  a  pressure  of  not  less  than  20  Ibs.  per 
sq.  in.,  and  by  the  simple  device  of  two  discharge  valves,  one 
loaded  and  one  free,  the  vaporiser  is  fed  with  oil  at  20  Ibs.  pres- 
sure. The  vapour  generated  is  thus  kept  at  20  Ibs.  as  the  vapour  jet 


Oil  Engines  437 

produces  sufficient  resistance.  If  the  pump  sends  too  much  oil, 
then  the  liquid  level  in  the  vaporiser  rises,  and  the  increase  in 
vapour  pressure  holds  the  lift  valve  down  and  allows  more  oil  to 
discharge  by  the  loaded  valve.  The  lamp  thus  just  gets  oil 
enough  to  generate  vapour  at  20  Ibs.  By  keeping  the  lamp 
chamber  under  considerable  pressure  it  is  found  that  the  small  jet 
hole  does  not  choke  up ;  if  the  pressure  be  lowered,  however,  the 
hole  rapidly  chokes  up  with  carbon.  This  is  obviously  due  to 
the  fact  that  by  boiling  under  high  pressure  the  oil  decomposes 
into  lighter  oils  which  do  not  readily  carbonise,  as  explained  in  the 
previous  chapter.  In  stopping  the  lamp  it  should  be  stopped 
suddenly  by  dropping  the  pressure  rapidly  ;  by  doing  this  the 
hole  escapes  being  choked  up.  Every  morning  before  starting  the 
vapour  hole  should  be  pricked  out  with  a  very  fine  needle. 

The  vaporiser  should  be  cleaned  out  every  week  ;  this  is 
accomplished  by  taking  off  the  scraped  cover,  which  is  held  on  by  a 
bolt,  and  putting  in  a  steel  rimer  in  succession  to  the  four  bored- 
out  holes  of  the  vaporiser.  By  turning  round  the  rimer  the 
carbon  or  coke  which  has  formed  in  a  week's  run  is  easily  cleared 
out. 

Tests  and  Oil  Consumption. — A  Crossley  engine,  declared  of 
7j  brake  HP,  was  tested  at  the  Cambridge  Royal  Agricultural 
Show.  Its  dimensions  were:  Cylinder  7  ins.  diameter:  stroke 
15  ins.  ;  weight  32^  cwts.  ;  the  speed  per  minute  210  revolutions. 
During  the  test  the  engine  ran  admirably,  and  required  very  little 
attention  ;  the  average  time  taken  to  start  was  16  minutes,  the 
maximum  time  taken  being  19  minutes,  and  the  minimum  13. 
One  attendant  only  was  required.  As  the  result  of  the  three 
days'  test,  the  engine  developed  on  an  average  6*28  brake  HP,  and 
consumed  -90  Ib.  of  Russoline  oil  per  brake  HP  per  hour.  At  a 
full- power  trial,  lasting  for  two  hours,  the  engine  developed  yoi 
brake  HP,  and  indicated  7-9,  running  at  a  mean  speed  of  200-9 
revolutions  per  minute.  The  oil  used  was  73  Ib.  per  IHP  per 
hour,  and  '82  Ib.  per  brake  HP  per  hour.  On  a  half-power 
trial  the  engine  developed  372  brake  HP  on  a  consumption  of 
i  -33  Ib.  of  Russoline  per  brake  HP  per  hour,  the  speed  being 
198-4  revolutions  per  minute.  Running  entirely  without  load 
at  190  revolutions  per  minute,  the  engine  consumed  2-53  Ibs.  of 


438 


Oil  Engines 


oil  per  hour.  Fig.  209  is  an  indicator  diagram  taken  frcm  this 
engine,  from  which  it  will  be  seen  that  the  maximum  pressure  of 
explosion  was  nearly  240  Ibs.  absolute,  and  the  pressure  of  com- 
pression about  80  Ibs.  absolute.  The  mean  available  pressure 
during  the  two  hours'  run  was  72^2  Ibs.  per  square  inch,  the  mean 
number  of  cylinder  explosions  per  minute  being  75*3.  The  oil 
consumed  by  the  Crossley  engine  is  remarkably  low,  "82  Ib.  of 

Ib perSfym. 
dbs. 
i+o 

220 


20 


FIG.  209. — Crossley  Oil  Engine  (diagram). 
Average  card,  two  hours'  full  power  trial.     Russoline  oil. 

Russoline  oil  per  brake  HP  per  hour  representing  an  expenditure 
for  fuel  of  -37^.  Another  trial  of  the  Crossley  engine  was  made 
at  the  Show  with  Broxbourne  oil.  The  power  indicated  was 
8-4,  the  brake  power  7*63,  the  engine  running  at  a  mean  speed 
of  199*84  revolutions  per  minute.  The  mean  effective  pressure 
was  63-6  Ibs.  per  square  inch,  and  the  oil  per  IHP  per  hour, 
•72  Ib.  ;  and  per  brake  HP  per  hour,  -785  Ib.  Although  the 


Oil  Engines  439 

engine  runs  with  less  of  this  oil  per  HP,  yet  it  is  to  be  remem- 
bered that  the  oil  costs  $>\d.  per  gallon,  and  is  not  so  economical 
from  a  monetary  point  of  view  as  Russoline  oil. 

Tangye  Oil  Engine. — This  engine  is  made  under  Pinkney's 
patents,  and  it  resembles  Crossley's  oil  engine  in  this,  that  the  oil 
is  vaporised  in  a  separate  vaporiser,  but  the  air  charge  is  wholly 
passed  through  the  vaporiser  to  carry  the  vapour  into  the  cylinder, 
and  the  air  so  used  is  not  subjected  to  any  preliminary  heating. 
The  ignition  is  effected  by  incandescent  tube.  The  construction 
and  operation  are  as  follows  : 

Fig.  210  shows  a  vertical  section  and  plan  of  the  oil  attach- 
ment to  a  Tangye  gas  engine.  The  vaporiser  is  a  bottle-shaped 
vessel  A  always  in  direct  communication  with  the  combustion 
space  of  the  engine  by  the  passage  B.  c  is  the  inlet  valve  to  the 
engine  ;  it  is  automatic,  and  is  held  to  its  seat  by  a  spring.  D  is  the 
air  inlet  passage.  E  is  the  oil  supply  aperture  which  terminates 
in  a  small  hole  F  opening  on  the  seat  of  the  valve  c  and  conse- 
quently opened  and  closed  by  it.  G  is  a  coil  lamp  of  the  Etna 
type,  i  is  the  igniting  tube  opening  to  the  vaporiser.  H  is  a  bracket 
for  supporting  the  lamp  G  in  its  successive  positions  under  the 
vaporiser  and  under  the  igniting  tube,  j  is  a  casing  surrounding 
the  igniting  tube,  and  K  a  casing  surrounding  the  vaporiser.  The 
lever  L  (plan)  operates  a  slide,  which  causes  the  hot  gases  from  the 
lamp,  to  pass  either  round  the  vaporiser  or  by  the  tube  funnel  j. 
To  start  the  engine  the  lamp  G  is  first  lit  in  the  manner  of  the  Etna 
lamp  and  the  vaporiser  A  is  sufficiently  heated.  The  lamp  is 
then  shifted  out  on  the  bracket  H,  and  the  tube  i  is  raised  to 
incandescence.  The  engine  is  then  ready  to  start  by  turning 
the  fly-wheel.  When  in  operation,  on  the  suction  stroke  air 
enters  by  the  valve  c,  and  at  the  same  time  oil  discharges  by  the 
aperture  F,  mixes  with  the  entering  air,  and  falls  on  the  vaporiser 
when  it  is  vaporised,  and  passes  into  the  cylinder  with  the  air. 
On  the  compression  stroke  the  inflammable  mixture  is  com- 
pressed and  ignites  at  the  igniting  tube  i,  producing  a  working 
explosion.  When  the  valve  c  closes,  the  oil  supply  is  also 
closed. 

When  governing,  the  governor  holds  open  the  exhaust  valve 
so  that  the  exhaust  gases  are  alternately  drawn  into  and  discharged 


440 


Oil  Engines 


from  the  cylinder  ;  during  this  action  the  valve  c  is  held  shut  by 
its  spring,  and  no  oil  or  air  enters  the  cylinder.     When  the  exhaust 


FIG.  2io.--Tangye  Oil  Engine. 


Oil  Engines  44! 

valve  opens  again,  the  oil  and  air  enter  the  vaporiser  and  the 
explosions  begin  again. 

The  oil  is  fed  by  gravity  from  an  oil  reservoir  mounted  above 


the   engine  by  a  pipe  to   the  passage  E  ;  adjusting  devices  are 
applied  at  the  reservoir  end. 

The  engine  is  a  very  simple  one,  but  in  the  author's  opinion 


442 


Oil  Engines 


all  systems  of  feeding  oil  by  gravity  are  bad,  and  with  large 
engines  such  systems  are  likely  to  be  dangerous. 

The  author  is  unaware  of  any  independent  tests  of  this 
engine, 

Fielding  6°  Platfs  Oil  Engine. — Fig.  211  is  a  general  view 
of  Messrs.  Fielding  &  Platt's  oil  engine.  Fig.  212  is  a  section 
through  the  vaporiser,  and  the  admission  port  to  the  engine 
cylinder.  In  this  engine  the  vaporiser  and  igniter  tube  are 
combined.  A  is  the  vaporiser,  B  the  combined  vaporiser  and 
igniter  tube,  c  is  an  air  heating  tube,  and  D  is  a  valve  com- 
municating between  the  vaporiser  and  the  igniter  tube.  The 


FIG.  212.—  Fielding  &  Platt's  Oil  Engine  (section  through  vaporiser). 


whole  system,  A,  B,  and  c,  is  inclosed  within  a  casing  E  and  heated 
up  by  means  of  a  lamp  F.  This  lamp  is  of  substantially  the  same 
construction  as  the  Etna,  described  at  page  431  of  this  work.  That 
lamp  has  an  air  reservoir  G  and  an  air  pump  H,  and  the  lamp  part 
F  is  arranged  to  produce  a  vapour  jet  which  sucks  in  by  induction 
sufficient  air  to  form  a  strong  blue  Bunsen  flame.  In  this  engine 
the  exhaust  and  air  inlet  valves  are  situated  opposite  each  other, 
opening  into  the  same  port.  In  oil  engines  this  is  a  highly 
desirable  arrangement,  because  it  is  advisable  to  heat  the  main 
air  supply  to  some  extent  as  it  enters  the  engine,  and  this  is  better 
done  by  causing  the  air  to  impinge  upon  the  hot  exhaust  valve 
and  pass  through  the  hot  exhaust  port  before  reaching  the  engine 


Oil  Engines  443 

cylinder.  To  start  the  engine  the  lamp  is  ignited  and  the  igniter 
tube,  vaporiser  tube,  and  air  tube  are  heated  up.  Oil  is  then 
injected  by  means  of  a  small  suction  pump  and  discharged  by 
the  jet  a  into  the  vaporiser  A  ;  on  the  suction  stroke  of  the  engine 
the  air  valve  i  opens,  and  air  is  drawn  into  the  engine  cylinder. 
At  the  same  time  air  passes  by  means  of  a  small  air  inlet 
aperture  K  through  the  air  heating  tube  c  to  the  chamber  b,  and 
thence  to  the  vaporiser  tube  A.  The  valve  D  is  opened  by  a  cam 
during  the  suction  stroke,  and  the  air  and  vapour  pass  together 
through  the  igniter  tube  B  into  the  cylinder.  The  charge  of  oil 
is  thus  sucked  through  at  each  stroke  and  taken  into  the  engine 
cylinder  by  a  small  quantity  of  air,  there  to  mix  with  a  larger 
quantity  of  air  already  in  the  cylinder.  The  port  L  is  somewhat 
large,  and  it  becomes  hot  by  the  exhaust  gases  and  by  the 
explosion,  and  so  maintains  the  vapour  without  condensation  as 
it  enters  the  cylinder. 

An  engine  was  exhibited  by  Messrs.  Fielding  &  Platt  at  the 
Cambridge  Show.  Its  dimensions  were— diameter  of  cylinder 
8|  ins.,  stroke  16  ins.,  weight  of  engine  53  cwts.,  declared  speed 
170  revolutions  per  minute.  In  this  engine  all  the  valves,  air 
valve,  vapour  valve,  and  exhaust  valve  are  actuated  from  one  cam, 
and  the  governor  of  the  usual  hit-and-miss  type  cuts  out  explo- 
sions when  the  engine  exceeds  its  speed  by  holding  open  the 
exhaust  valve  and  keeping  the  air  and  vapour  valves  closed.  The 
piston  thus  runs  to  and  fro,  taking  the  exhaust  gases  into  the 
cylinder  from  the  exhaust  pipe,  and  returning  them  to  it  again. 
During  the  trial  at  the  show  the  lamp  is  stated  to  have  given  too 
little  heat,  and  consequently  rendered  the  ignitions  late.  The 
engine  ran  very  steadily,  however,  and  started  very  readily  with 
one  attendant  only,  twenty-two  minutes  being  consumed  in 
heating  up.  As  the  late  ignition  could  not  be  remedied  at  once 
the  engine  was  withdrawn  from  the  test. 

Tests  and  Oil  Consumption. — Messrs.  Fielding  &  Platt  have 
been  good  enough  to  send  the  author  particulars  of  the  results  ob- 
tained with  the  engine  (see  table,  p.  444),  together  with  a  diagram 
from  which  fig.  213  has  been  prepared.  The  tests  and  diagram 
show  the  engine  now  to  be  in  thoroughly  good  order. 

The  results  are  very  good  indeed  ;  a  consumption  of  o'8o  Ib. 


444 


Oil  Engines 


of  Russoline  oil  per  brake  HP  hour  is  superior  to  that  given  by 
the  first  prize  engine  at  the  Cambridge  Show. 

TESTS  OF   A  3   HP  NOMINAL  FIELDING  &   PLATT   OIL  ENGINE 
MADE   BY  MESSRS.  FIELDING  &  PLATT  ON  NOVEMBER  22  AND  23,  1894. 


Power 

Full 

Half 

Light 

Full 

Duration  of  test 

i  hour 

I  hour 

i  hour 

3  hours 

Revolutions  per  minute    . 

220 

225                 230 

222 

Explosions  per  minute 

IOO 

84 

18 

IOO 

Nett  brake  load 

63  Ibs. 

33  lbs- 

— 

63  IDS. 

Diameter  brake  circle 

4  ft. 

4  ft. 

4  ft. 

4  ft. 

Brake  HP                                     .   i        5-28 

2-8 

5'3 

Oil  per  hour  in  Ibs.  (Russoline)           475 

3  '5 

i  '3 

4'24 

Oil  per  brake  HP  hour     .         .       0^90  Ib. 

raslb. 

0-80  Ib. 

Available    pressure  average  of 

' 

four  diagrams,  79  Ibs. 

Fig.  213  is  a  diagram  from  a  similar  3  HP  nominal  engine 
taken  in  a  test  made  on  October  22,  1895,  which  also  shows  the 
excellent  result  of  '8  Ib.  of  oil  per  brake  HP  hour.  During  that 
test  the  engine  gave  5-5  HP  on  the  brake  at  219  revolutions  per 
minute,  the  compression  was  40  lbs.  and  the  maximum  pressure  of 
the  explosion  was  140  lbs.,  while  the  available  pressure  was  63  lbs. 


FIG.  213.— Fielding  £  Platt's  Oil  Engine  (diagram). 

Messrs.  Fielding  &  Platt  state  that  ten  minutes  suffice  for  the 
heating  of  the  igniter  and  vaporiser,  and  that  having  started  the 
lamp  it  is  only  necessary  for  the  driver  to  go  round  the  engine 
and  examine  and  fill  up  lubricators  ;  after  this  the  vaporiser  will 
be  hot  enough,  and  on  giving  the  fly-wheel  a  turn  or  two  the 
engine  starts.  A  half  compression  cam  is  provided  to  ease  the 
starting. 


Oil  Engines 


445 


This  engine  is  extremely  simple,  and  the  timing  valve  is 
entirely  dispensed  with,  the  igniter  tube  B  being  at  all  times  open 
to  the  cylinder.  The  engine  is  exceedingly  economical  at  light 
loads  as  well  as  at  full  load. 


FIG.  214.— Campbell  Oil  Engine  (section  through  vaporiser  and  igniter). 

Campbell  Oil  Engine. — The  Campbell  engine  resembles  the 
Tangye  engine  in  its  vaporising  arrangements.  There  are  only 
two  valves,  inlet  and  exhaust  ;  the  air  inlet  is  automatic  and  the 
exhaust  is  operated  in  the  usual  manner.  In  this  engine  also  there 
are  no  oil  pumps  ;  the  vaporiser  is  fed  by  gravity,  and  so  is  the 


446 


Oil  Engines 


lamp.  Ignition  is  produced  by  incandescent  tube,  and  the 
vaporiser  and  tube  are  heated  by  a  lamp.  The  engine  resembles 
the  Tangye  in  passing  the  whole  of  the  air  charge  through  the 
vaporiser  to  carry  off  the  vapour  when  formed.  Fig.  214  is  a 
section  through  the  vaporiser  and  igniter  tube  of  the  Camp- 
bell oil  engine.  Fig.  215  is  a  horizontal  section  showing  the 
exhaust  valve  and  the  end  of  the  vaporiser.  Fig.  216  is  a  side 


FIG.  215. — Campbell  Oil  Engine  (horizontal  section  through  exhaust  valve). 

elevation  of  the  end  of  the  engine,  showing  the  operation  of  the 
governor. 

An  automatic  inlet  valve  A  serves  for  admission  of  the  whole 
air  charge  to  the  cylinder  by  way  of  the  vaporiser  B  and  passage 
G.  The  oil  is  fed  by  gravity  and  passes  through  the  supply  pipe 
c  to  an  annular  channel  D  round  the  seat  of  the  valve  A,  and  is 
injected  through  perforations  E  to  mix  with  the  air  when  the  valve 


Oil  Engines 


447 


opens.  This  valve,  like  the  Tangye,  resembles  the  gas  and  air 
valve  first  introduced  by  Clerk.  On  the  suction  stroke  of  the 
engine,  air  enters  by  the  valve  A,  and  oil  entering  with  it  is  carried 
through  the  vaporiser,  and  the  mixture  of  inflammable  vapour  and 
air  passes  into  the  engine  cylinder  by  the  passage  G  ;  this  passage 
G  leads  into  the  exhaust  port,  as  clearly  seen  at  fig.  215,  and  thus 
one  port  serves  for  the  admission  of  the  charge  to  the  cylinder  and 
the  discharge  of  the  exhaust  products.  The  igniter  tube  H  is 


FIG.  216.  —  Campbell  Oil  Engine  (side  elevation  of  cylinder  end). 

screwed  into  the  bend  of  the  vaporiser  and  is  always  in  open  com- 
munication with  it.  The  lamp  which  heats  the  tube  also  heats  the 
vaporiser,  but  while  at  work  the  heat  of  the  explosions  is  sufficient 
to  keep  up  the  vaporiser  temperature.  The  explosion  ensues 
upon  compression,  the  inflammable  mixture  being  forced  into  the 
hot  tube.  This  engine,  however,  is  found  to  ignite  without  the 
tube  after  running  for  some  time. 

The  governing  is  accomplished  by  a  ball  governor  I,  fig.  216, 
which  controls  the  exhaust  valve  j.     This  valve  is  opened  at  every 


443 


Oil  Engines 


exhaust  stroke  by  the  sliding  piece  K,  which  at  one  end  of  its  stroke 
strikes  the  pin  L,  and  by  moving  the  lever  M  opens  the  exhaust 
valve.  When  the  engine  speed  rises  above  normal  the  governor 
sleeve  rises  and  moves  the  lever  N  and  link  o  ;  this  interposes  the 
small  plate  P  between  the  outer  end  of  the  lever  M  and  the  stationary 
bracket  Q.  The  exhaust  valve  spring  is  thus  prevented  from 
pulling  the  valve  back  to  its  seat  until  the  speed  falls  again.  The 


•/  '2 

FIG.  217.— Campbell  Oil  Engine  (diagram). 

holding  open  of  the  exhaust  valve  j  thus  prevents  the  suction 
of  a  charge  of  oil  and  air  through  the  automatic  valve  A.  This 
engine,  like  the  Tangye,  is  very  simple,  but  in  the  author's  opinion 
the  oil  fed  by  gravity  is  troublesome,  and  in  all  but  small  engines 
is  also  likely  to  be  dangerous. 

Tests  and  Oil  Consumption. — A  Campbell  engine  was  tested 
at  the  Cambridge  Royal  Agricultural  Show.  The  engine  was  de- 
clared as  of  6  HP  nominal,  the  diameter  of  the  cylinder  was  7^  ins., 


Oil  Engines 


449 


and  the  stroke  12  ins.  The  declared  revolutions  were  240  per 
minute.  The  engine  weighed  27  cwts.  In  a  three  days'  test  it 
gave  475  brake  HP  on  an  oil  consumption  of  1-15  Ib.  Russoline 
oil  per  brake  HP.  In  a  subsequent  full  power  test  the  engine  gave 
4-81  brake  HP,  and  indicated  5-9  horse  on  a  consumption  of  -93 
Ib.  of  oil  per  I  HP  per  hour,  and  1-12  per  brake  HP  per  hour. 
The  average  speed  during  the  trial  was  2077  revolutions  per 
minute,  and  the  average  pressure  developed  in  the  cylinder  was 
65-5  Ibs.  Fig.  217  is  a  dia- 
gram taken  from  the  Camp- 
bell engine  during  a  two  hours' 
test.  The  Campbell  ran  with- 
out load  at  211  revolutions  per 
minute  on  a  consumption  of 
2^32  Ibs.  of  oil  per  hour. 

Britannia  Oil  Engine. — 
The  Britannia  engine  is  the 
invention  of  Mr.  Roots,  and  in 
it  also  the  air  heater,  vaporiser, 
and  incandescent  tube  are 
neatly  combined  in  one  cast- 
ing. The  oil  feed  arrangement 
too  is  ingenious,  and  dis- 
penses with  a  pump  of  the 
ordinary  type.  Fig.  218  is  a 
section  showing  the  air  heater, 
vaporiser,  and  ignition  tubes, 
as  also  the  air  inlet  valve  of 
the  engine.  Fig.  219  is  an 
end  elevation  part  in  section 
showing  the  action  of  the  oil 
feed.  Oil  is  fed  to  the  oil  bath  A,  fig.  219,  and  is  kept  at  a  con- 
stant level  in  that  bath  by  the  overflow  hole  a.  A  spindle  B  is 
reciprocated  to  and  fro  by  the  levers  c,  D,  and  a  cam  E  on  the 
valve  shaft  F.  The  governor  lifts  the  lever  G,  carrying  the  trip 
piece  H,  shown  in  dotted  lines,  and  so  long  as  this  trip  piece  is 
held  opposite  the  operating  edge  of  the  lever  D,  the  spindle  is 
moved.  When  the  governor  lifts  the  trip  piece  the  spindle  B 

G  G 


FIG.  218 — Britannia  Oil  Engine 
(section  through  vaporiser). 


450 


Oil  Engines 


remains  stationary.  Grooves  b  are  cut  round  the  spindle  B  ; 
these  grooves  fill  with  oil,  and  on  pulling  the  spindle  P,  through 
to  the  chamber  i  the  oil  falls  off  or  is  blown  off  by  the  passing  air. 
This  chamber  is  seen  at  i  in  fig.  218  as  well  as  in  the  end  elevation. 
The  upper  part  of  that  figure  shows  a  spiral  or  louvre  deflecting 
plate  device,  forming  part  of  the  casing  K  ;  air  enters  at  the  upper 
part,  passes  over  the  deflecting  plates  which  are  heated  by  the 
flame,  serving  to  heat  the  ignition  tube  L.  The  ignition  tube  L  is 
placed  in  a  circular  casing,  the  upper  part  of  which  carries  the 


FIG.  219.— Britannia  Oil  Engine  (oil  feed  and  governing). 

deflecting  plates    referred   to,    and   the    lower    part    carries    the 
vaporiser  M.     The  air  enters  the  engine  by  way  of  the  deflecting 
plates,  passes  over  them,  and  becomes  heated,  then  strikes  upon 
the  oil  supply  spindle  B  and  removes  the  oil  from  the  grooves, 
carrying  it  into  the  vaporiser,  and  then  carrying  the  oil  from  the 
vaporiser  M  to  the  air  inlet  valve  N,  and  thence  by  the  inlet  port  o 
to  the  engine  cylinder.     Ignition  is  caused  at  the  proper  time  by ' 
the  compression  of  the  combustible  mixture  into  the  hot  ignition  i 
tube  ju 


Oil  Engines 

The  lamp  used  in  the  Roots  engine  is  shown  at  fig.  220,  which 
is  an  elevation  part  in  section.  It  is  of  the  now  standard  type 
like  the  Etna,  and  consists  of  a  tube  A  bent  round  upon  itself  to 
form  an  elongated  loop.  At  the  end  B  of  the  loop  is  arranged  a 
small  opening  c,  in  which  a  conical  pin  D  fits.  The  point  of  the 
pin  projects  through  the  small  hole  E,  and  so  forms  an  adjustable 
annular  orifice.  An  oil  vessel  F  is  connected  to  the  tubs  A.  and 


FIG.  220.— Britannia  Oil  Engine  (lamp). 

has  attached  to  it  a  small  air  pump  G.     Outside  the  bent  pipe  A 
is  a  sleeve  or  hood  H  open  at  both  ends. 

To  start  the  lamp  the  tube  A  and  hood  H  are  first  heated  by 
a  piece  of  waste  soaked  in  oil  and  lighted.  Air  is  pumped  into 
the  reservoir  F  by  means  of  the  small  air  pump  G  until  the  oil  is 
forced  through  the  asbestos  I  contained  in  the  tube  ;  the  oil  heats 
and  boils  off,  discharging  as  a  strong  jet  at  the  annular  orifice 


452 


•Oil  Engines 


made  by  the  pin  D.  The  jet  is  lit  and  the  flame  heats  the  bent 
tube  and  is  discharged  out  of  the  hood  H  as  a  fierce  blue  smoke- 
less flame. 

This  lamp  is  similar  to  the  others,  but  the  small  points  of  detail 
peculiar  to  it  are  interesting. 

The  Britannia  engine,  like  the  Tangye  and  Campbell,  takes  in 
the  whole  air  charge  through  the  vaporiser. 

Tests  and  Oil  Consumption.  —  One  of  the  Britannia  engines  was 


-pe 


in 


•I  "2  "3  ^  'S 

FIG.  221. —Britannia  Oil  Engine  (diagram). 

tested  at  the  Cambridge  Show  ;  its  dimensions  were — diameter  of 
cylinder  y|  ins.,  stroke  13  ins.,  declared  revolutions  per  minute  235, 
weight  of  engine  33  cwts.,  declared  power  7  brake  horse.  On  a 
three  days'  test  the  engine  developed  on  an  average  6-15  brake 
horse  and  consumed  1-49  Ib.  of  oil  (Russoline)  per  brake 
horse  hour.  On  the  subsequent  full  power  test,  lasting  for  two 
hours,  the  engine  gave  6*21  brake  HP  and  indicated  8*4  HP. 
Running  at  240  revolutions  per  minute  and  giving  a  mean  effec- 
tive pressure  of  47-3  Ibs.  per  sq.  in.,  the  oil  consumed  was 


Oil  Engines 


453 


1-25  lb.  IHPhour,  and  r68  Ib.  per  brake  HP  hour.  On  half 
power  the  engine  developed  3-96  brake  horse,  consuming  1-67  lb. 
per  brake  horse  hour.  Running  light  without  load  the  engine 
made.  256  revolutions  per  minute,  and  consumed  1-44  lb.  of 
Russoline  oil  per  hour.  It  is  a  somewhat  remarkable  fact  that 
this  engine,  which  consumed  the  largest  amount  of  oil  per  HP 
of  any  of  the  engines  tested  at  the  Cambridge  Show,  ran  with 
no  load  at  full  speed  on  the  lowest  consumption  of  oil  of  any. 
Fig.  221  is  a  diagram  from  this  engine  taken  during  the  two 
hours'  trial.  In  the  trials  this  engine  was  found  to  require  1 2  and 
13  minutes  to  start ;  on  one  occasion  however  it  took  24^  minutes 
to  heat  up  for  starting. 

Clarke,  Chapman  &>  Co.'s  Oil  Engine. — A  vertical  longi- 
tudinal section  of  this  engine  is  shown  at  fig.  222,  and  a 
transverse  section  at  fig.  223.  The  engine  is  peculiar  among 
petroleum  engines  in  dispensing  entirely  with  lift  valves  and 
depending  for  all  the  operations  of  the  engine  upon  a.  rotating 
plug  valve.  This  valve  is  rotated  by  a  shaft  driven  at  one  fourth 
of  the  speed  of  the  crank  shaft,  and  by  its  rotation  the  whole  of 
the  operations  of  admission  and  exhaust  are  performed ;  the 
ignition  is  obtained  by  means  of  the  electric  spark.  Although  the 
vaporising  and  valve  actions  of  this  engine  present  externally  a 
simple  appearance,  yet  internally  they  are  extremely  complex,  too 
complex  in  the  author's,  opinion  to  be  suitable  for  the  rough  con- 
ditions of  public  use.  A  is  the  plug  valve  rotated  as  described  by 
the  valve  shaft  B.  The  port  A1  through  the  valve  is  the  exhaust 
port  which  connects  by  means  of  another  port  A2  with  the  exhaust 
pipe.  A3  is  one  of  the  air  and  charge  inlet  ports  communicating  by 
means  of  a  port  A5  with  the  air  supply  passage  c  opening  through 
the  throttle  valve  D  to  the  mixing  chamber  for  air  and  vapour  E. 
The  exhaust  discharges  by  the  pipe  F  round  the  conical  vaporising 
chamber  G  and  out  at  the  exhaust  pipe  F'.  The  air  supply  is  also 
heated  by  the  exhaust  gases,  and  an  air  jacket  is  formed  round  the 
exhaust  pipe  at  H.  The  air,  when  heated,  passes  by  way  of  the 
passage  i  into  the  mixing  chamber  E,  and  the  oil,  which  is  forced 
from  the  oil  supply  reservoir  K  by  air  pressure  into  the  vaporiser, 
is  vaporised  and  passes  into  the  mixing  chamber  by  way  of  a 
similar  passage  L,  and  there  mixes  with  a  further  portion  of  hot 


Oil  Engines  455 

air.  A  small  portion  of  air  passes  through  the  vaporiser  to 
carry  off  the  oil  vapour,  and  this  portion  of  air  is  heated  also  by 
the  exhaust  gases.  The  engine  is  governed  by  throttling  the 
charge  admitted  by  means  of  the  throttle  valve  D  operated  from 
the  governor  shaft  M,  and  at  the  same  time  the  oil  supply  is  varied 
with  the  air  supply.  This  method  of  governing  is  not  a  good  one, 
and  must  result  in  a  somewhat  high  consumption  at  light  loads. 
The  difficulties  too  of  maintaining  the  working  surfaces  of  a  plug 
valve  under  the  trying  conditions  operating  in  a  gas  engine  have 
prevented  plug  valves  being  used  to  any  extent  except  for  the 
very  smallest  engines.  The  author  is  somewhat  surprised  that 
the  inventor  of  this  engine  (Mr.  Butler)  should  have  attempted  to 
use  a  plug  valve  under  the  vastly  more  difficult  conditions  of  a 
petroleum  engine.  To  start  the  engine  a  small  quantity  of 
benzoline  is  used,  which  is  supplied  until  all  the  parts  are  heated 
up  sufficiently.  An  engine  of  this  type  was  exhibited  at  the 
Cambridge  Show  ;  it  was  rated  at  6  HP  brake,  the  diameter  of 
the  cylinder  was  7^  ins.,  and  the  stroke  \2\  ins.  The  speed  was 
declared  to  be  350  revolutions  per  minute.  The  weight  of  the 
engine  was  35  cwts.  Owing  to  difficulties  with  the  engine  at  the 
Show,  however,  it  was  withdrawn  from  competition. 

Weyman  c^  Hitchcock's  Oil  Engine.—  This  engine  resembles 
the  Hornsby  and  Robey  engines  in  that  the  vaporiser  is  heated 
by  the  heat  of  the  explosions  and  exhaust  products  only.  In  it, 
however,  the  gases  are  ignited  by  an  incandescent  tube  raised  to 
incandescence  by  a  separate  lamp.  The  vaporiser  chamber, 
however,  communicates  with  the  cylinder  by  a  valve,  and  so  the 
engine  comes  under  this  particular  head.  The  oil  supply  is 
pumped  through  a  sight  feed  tube  D  to  the  top  of  the  vaporiser, 
as  shown  at  fig.  224,  where  D  is  a  sight  feed  tube  and  c  the 
vaporiser.  This  oil  with  a  small  proportion  of  air  passes  round 
an  annular  passage,  and  the  oil  gradually  vaporises  as  it  falls  and 
diffuses  into  the  air  accompanying  it.  The  oil  charged  with 
vapour  rises  through  a  series  of  holes  to  a  central  chamber  and 
then  passes  through  a  vapour  valve  into  the  cylinder,  where  it 
meets  with  an  additional  air  supply.  The  ignition  tube  is  heated 
by  an  external  lamp  operated  by  a  powerful  air  blast  produced 
from  an  air  pump  on  the  engine.  Fig.  225  is  an  end  elevation  of 


456  Oil  Engines 

this  engine  duly  lettered  with  references  printed  underneath. 
From  this  it  will  be  seen  that  the  engine  is  of  somewhat  complex 
construction. 

Tests  and  Oil  Consumption. — An  engine  exhibited  at  the 
Cambridge  Show  was  declared  as  of  5  brake  HP,  the  cylinder 
was  6  \  ins.  diameter  by  13  ins.  stroke,  and  the  declared  speed 
was  250  revolutions  per  minute.  On  a  three  days'  test  the  engine 
developed  a  mean  power  of  6*2 1  brake  horse  and  consumed 
1-13  Ib.  of  oil  per  brake  horse  hour.  The  engine  took  from  14 
to  1 7  minutes  to  start.  At  a  full-power  test  lasting  for  two  hours 


FIG.  224 — Weyman  &  Hitchcock's  Oil  Engine  (part  section). 

A,  cylinder  ;  B,  combustion  chamber  ;  c,  oil  inlet  ;  n,  sight  feed  tube  ;  E,  pump ; 
F,  main  air  supply  ;  i,  lubricator. 

the  same  engine  developed  6*5  IHP,  473  brake  horse  on  a  mean 
speed  of  2597  revolutions  per  minute,  and  consumed  *8y  Ib. 
of  oil  per  IHP  hour,  and  1-19  Ib.  per  brake  HP  hour.  At 
half  load  the  engine  developed  2-58  brake  horse  ;  the  oil 
consumed  was  1*57  Ib.  per  brake  horse  hour.  Running  without 
load  at  207  revolutions  per  minute  the  engine  consumed  277  Ibs. 
of  oil  per  hour.  Fig.  226  is  a  diagram  from  the  engine. 

Wells  Brothers'  Oil  Engine. — Fig.  227  is  an  end  elevation  of 
the  Wells  engine,  showing  the  important  parts.    Professor  Capper, 


Oil  Engines 

Agricultural  Socie'y.  Ascribes  it  as 

'There  is  but  one  rocking  lever  to  actuate  all  the  valves      It 
is  driven  by  a  cam  on  the  lay  shaft,  in  opposition  to  a  powerful 
sp,ral  spring.     When  running  at  normal  speed,  the  spring  draw 
the  lever  home,  closing  the  exhaust  valve,  and  opening  the  vapour 


FIG.  225 Weyman  &  Hitchcock's  Oil  Engine  (end  elevation). 

a,  side  lever  '  c,  governor  ;  de,  rocking  levers  working  oil  and  air  valves  ;  g,  air  inlet 
pipe  ;  Q,  oil  reservoir  for  lamp  ;  R,  oil  supply  pipe  to  lamp  ;  s,  air  blast  pipe  ;  i ,  air 
pump  ;  u,  lamp  reservoir  ;  w,  oil  pump  ;  x,  oil  pump  discharge  ;  Y,  oil  supply 
pipe  ;  z,  pet  cock. 

valve  at  the  required  moment.  When  running  too  fast,  the  hori- 
zontal catch,  which  has  been  lowered,  by  the  outward  movement 
of  the  valve  lever,  has  not  time  to  rise  clear  under  the  weight  of 
its  inner  end  before  the  return  of  the  vertical  lever,  which  there- 
fore is  arrested,  and  no  movement  of  the  valves  takes  place. 
The  exhaust  valve  is  then  kept  open,  and  the  vapour  valve  being 


458 


Oil  Engines 


closed,  an  idle  stroke  occurs,  the  oil  valve  at  the  same  time  emit- 
ting a  charge  from  the  vaporiser.  The  oil  valve  is  a  rotating  taper 
plug,  driven  by  a  link  off  a  rocking  lever.  A  cavity  in  this  plug 
measures  out  a  charge  of  oil  at  each  vibration,  and  drops  it  upon 
a  heated  diagonal  plate,  down  which  it  runs  and  is  vaporised.  An 
adjustment  is  provided  by  which  the  quantity  of  oil  at  each  charge 
can  be  regulated,  and  the  valve  box  is  filled  by  gravity  from  a 
raised  tank.  This  arrangement  is  secure  against  injury  from  dirt, 
as  anything  that  is  small  enough  to  pass  into  the  oil  plug  would 
simply  fall  to  the  bottom  of  the  vaporising  chamber,  and  there 


Ib.per  A 
al&ol 
160 
140 
/20 
IOO 
80 

60 
40 

20 
a 

Sty.  in. 
<ute 

\ 

\ 

s 

\ 

s 

\ 

l 

N 

( 

"•^ 

^"N 

—  -^ 

-^ 

—  « 

^^ 

^> 

•"•^ 

*-^. 

} 

/  -2  *3  '4 

FIG.  226. — Weyman  &  Hitchcock's  Oil  Engine  (diagram). 


be  retained.  The  lamp  which  heats  the  vaporiser  is  completely 
inclosed  in  a  cast-iron  combustion  chamber,  the  blast  being  sup- 
plied by  an  air  pump.'  '  The  makers  claim  that  little,  if  any, 
gasification  takes  place,  as  the  vaporiser  is  water-jacketed,  and  so 
not  overheated.  This  view  is  to  some  extent  upheld  by  the  fact 
that  the  cylinder  works  without  lubrication,  beyond  that  of 
inclosed  oil  vapour.' 

Tests  and  Oil  Consumption.—  An  engine  of  this  type  was 
exhibited  at  the  Cambridge  Show  of  a  declared  4  HP  nominal. 
The  cylinder  was  8J  ins.  diameter,  and  15  ins.  stroke,  the  declared 


Oil  Engines 


459 


speed  being  165  revolutions  per  minute.  This  engine  gave  on  the 
three  days'  test  a  mean  power  of  5-96  horse,  and  consumed  ro6 
Ib.  of  oil  per  brake  horse  hour.  The  engine  was  very  easily 
started,  starting  usually  in  from  10  to  17  mins.  A  full  power  test 
of  two  hours  gave  an  indicated  power  of  7-3,  and  a  brake  power  of 
6-46  horse,  the  oil  consumption  being  -93  Ib.  per  IHP  per  hour 
and  i  -04  per  brake  horse  hour.  The  engine  ran  at  an  average 
speed  of  184  revolutions. 

At  half- power    3-52   brake  vrQ 

horse    was   given,    and    a  --  J 

consumption  of  1-59  Ib.  of 
oil  per  brake  horse.  Run- 
ning without  load  the  en- 
gine used  i  -96  Ib.  of  oil  per 
hour  at  165  revolutions  per 
minute.  Fig.  228  is  a  dia- 
gram taken  from  the  Wells 
engine. 

Applications  of  Petro- 
leum Engines. — Petroleum 
engines  have  now  been 
applied,  in  addition  to  the 
ordinary  purposes  for  which 
stationary  engines  are  re- 
quired, tO  the  propulsion  A,  vapour  valve  ;  c,  horizontal  catch  ;  D,  vaporiser 
*  door  ;  E,  exhaust  valve  ;  K,  trip  ;  L,  rocking  lever; 

Of    launches,     and     for     aC-  M,  oil  supply  cock  ;  N,  oil  supply  chamber  ;  o,  oil 

,  .  -.  r  supply  pipe  ;  P,  oil  supply  to  lamp  ;  Q,  automatic 

tuating  road  Carriages.   MOSt          explosion  counter ;  R,  link  working  oil  valve  ;  v, 

of  the  launch  engines  use       vaP°nser- 

,         ,.  ,,      .,  FIG.  227.— Wells  Oil  Engine 

gasoline  or  other  light  oil,  (end  elevation). 

and  so  present  no  peculia- 
rities which  need  be  studied  here.  It  will  be  observed  that  the 
author  has  not  described  any  of  the  oil  engines  produced  on  the 
Continent  or  in  America.  These  engines  are  without  exception 
engines  of  the  ordinary  gas  engine  type  using  gasoline  or  other 
light  oils  which  require  no  special  precautions,  and  indeed  are  not 
interesting  as  bearing  on  the  question  of  safe  heavy  oil  engines. 
The  engines  on  the  Continent  and  in  America  which  use  heavy  oil 
are  those  already  described  in  this  chapter  or  engines  following 


460 


Oil  Engines 


the  same  lines.  Many  ingenious  details  are  used  in  the  foreign 
oil  engines,  but  as  yet  British  inventors  appear  to  have  taken  the 
lead  in  the  task  of  devising  means  of  utilising  the  safe  lamp  oils 
of  commerce.  This  probably  is  due  to  the  somewhat  severe  legal 
restrictions  placed  upon  the  sale  and  storage  of  such  light  and 
inflammable  oils  as  gasoline,  benzine  or  petroleum  spirit,  restric- 
tions which  do  not  exist  in  the  laws  of  America  or  France.  The 
principal  engine  used  upon  the  Continent  for  marine  purposes  is 
that  of  Daimler. 

The  Daimler  engine  is  a  small  two-cylinder  engine  ;  the  two 


.n/. 


160 
140 
120 
100 

80 
6O 


•I  '2  3  -+  y 

FIG.  228  —  Wells  Oil  Engine  (diagram). 


cylinders  incline  at  an  angle  of  about  30°  to  each  other,  and  the 
connecting  rods  operate  on  a  common  crank  pin.  The  front  ends 
of  the  cylinders  are  closed  in,  and  the  front  ends  act  as  air  pumps. 
The  Otto  cycle  is  performed  by  each  piston,  but  each  cylinder  is 
supercharged  with  air  to  a  pressure  of  a  few  pounds  above 
atmosphere,  the  air  being  supplied  from  the  front  of  the  piston. 
By  this  device  a  high  average  pressure  is  obtained,  but  light  oil  is 
used  so  that  no  special  vaporising  arrangements  are  required. 

The  Daimler  Motor  Carriage.—  The  Daimler  motor  carriage  has 
come  into  considerable  prominence  in  connection  with  the  recent 
trials  of  horseless  carriages  in  France.  The  author  has  carefully 


'  Oil  Engines  46 1 

examined  one  of  these  carriages,  and  finds  that  it  contains  one 
of  the  ordinary  two-cylinder  Daimler  light  oil  motors,  which  is 
mounted  with  its  crank  shaft  axis  parallel  to  the  length  of  the 
carnage.  The  engine  is  started  by  a  handle  projecting  from  the 
front  of  the  carriage,  which  handle  drives  a  spindle  by  pitch  chain. 
When  the  engine  starts,  it  puts  a  stop  out  of  gear  and  disconnects 
the  chain.  The  engine  shaft  gears  into  a  friction  clutch,  which 
can  be  drawn  in  and  out  to  disconnect  the  engine  from  the 
carnage  wheels.  The  back  wheels  of  the  four-wheeled  carriage 
are  driven  by  a  shaft  carried  across  the  centre  of  the  carriage,  and 
operated  from  the  engine-driving  spindle  by  bevil  wheel  and 
opposing  bevil  wheels  so  geared  as  to  form  a  reversing  arrange- 
ment by  engaging  on  one  or  other  side  of  the  engine  bevil  wheel. 
The  spindle  carrying  the  engine  bevil  wheel  is  geared  to  the 
engine  shaft  by  means  of  change  wheels  of  the  ordinary  pinion 
and  spur  wheel  type,  four  sets  of  wheels  being  provided  which 
may  be  geared  one  pair  at  a  time  to  give  four  different  speeds 
without  varying  the  speed  of  the  engine.  The  two  front  wheels 
are  steering  wheels,  and  are  operated  by  a  lever  somewhat  like 
that  used  to  steer  a  Bath  chair.  The  rear  driving  wheels  of  the 
carriage  are  geared  to  the  cross  shaft  by  pitch  chains.  The  en- 
gine uses  light  oil  contained  in  a  small  reservoir  in  front  of  the 
driver.  The  mixture  is  ignited  by  means  of  two  platinum  tubes 
heated  to  incandescence  by  an  oil  flame  of  the  Bunsen  type.  The 
engine  when  started  runs  at  a  constant  speed,  and  the  whole  of 
the  operations  of  the  carriage  are  performed  by  means  of  levers, 
clutches,  change  wheels  and  brakes.  In  the  author's  opinion 
this  carriage,  ingenious  as  it  is,  will  not  find  much  use  in  England. 
A  carriage,  however,  using  heavy  oils  and  overcoming  the  diffi- 
culties would  probably  be  very  successful. 


' 


462  Oil  Engines 


CHAPTER  III. 

THE    DIFFICULTIES    OF    OIL    ENGINES. 

THE  reader  will  have  observed  from  the  description  of  thirteen 
different  examples  of  oil  engines  given  in  the  preceding  chapter, 
and  the  details  of  oil  consumption  and  efficiency,  that  the  oil 
engine  is  not  so  economical  from  a  heat  engine  point  of  view  as  a 
gas  engine  ;  that  is,  the  oil  engine  so  far,  for  a  given  number  of  heat 
units  entrusted  to  it  as  oil,  does  not  convert  so  large  a  proportion 
of  those  heat  units  into  indicated  work  as  a  gas  engine.  It  is  to 
be  remembered,  of  course,  that  as  yet  engineers  have  had  little 
experience  in  oil  engines  as  compared  with  gas  engines,  and  that 
probably  with  further  development  of  detail  the  heat  efficiency  of 
the  oil  engine  may  yet  be  considerably  increased.  The  lower 
efficiency  at  present  obtained  is  due  to  certain  difficulties  peculiar 
to  the  oil  engine,  which  do  not  occur  in  the  gas  engine.  These 
difficulties  are  present  to  some  extent  in  all  the  three  types  of 
engine,  but  in  some  types  to  a  greater  extent  than  in  others.  In 
the  earlier  engines  ignition  presented  a  formidable  difficulty,  which 
was  overcome  by  the  use  of  the  electric  spark.  Electric  methods 
of  ignition  are  very  objectionable  whether  used  in  gas  or  oil 
engines  ;  so  objectionable,  indeed,  that  no  gas  engine  at  present 
manufactured  in  Britain  uses  an  electric  igniter.  Electric  igniters 
require  a  battery,  an  induction  coil  and  insulated  points,  or  an 
electro-magnetic  device,  and  insulated  points  with  a  contact- 
•breaking  contrivance.  Either  of  these  forms  can  be  made  to  work 
quite  well  in  an  engineer's  hands  or  in  the  hands  of  anyone  used 
to  batteries  and  dynamos,  and  willing  at  the  same  time  to  devote 
considerable  attention  to  keeping  the  apparatus  in  order.  The 
public  in  this  country,  however,  who  use  gas  and  oil  engines  are 
'very  liable  to  allow  electric  contrivances  to  get  out  of  order,  and  it 


The  Difficulties  of  Oil  Engines  463 

has  always  been  the  author's  opinion  that  any  engine  with  an 
electric  igniting  device,  even  if  good  in  other  respects,  would  not 
attain  extended  use  in  Britain.  Curiously  enough  this  objection 
does  not  seem  to  weigh  much  with  the  Continental  public  or  with 
the  American  public,  as  many  engines  are  sold  on  the  Continent 
and  in  America  which  use  electric  igniting  devices.  The  nature 
of  safe  burning  oil  made  it  very  difficult  to  use  either  a  flame 
device  for  igniting  or  an  incandescent  tube  for  that  purpose.  It 
was  by  no  means  easy  and  evident  to  see  in  what  way  safe  heavy 
oil  could  be  treated  to  give  a  smokeless  heating  flame  of  the 
character  necessary  either  for  flame  ignition  or  incandescent  tube 
ignition.  The  production  of  the  type  of  lamp  described  at 
page  431  gave,  however,  an  easy  means  of  producing  a  smokeless 
heating  flame,  and  so  at  once  made  it  possible  to  use  that  simplest 
of  all  igniting  devices,  the  incandescent  tube.  In  the  author's 
opinion  the  incandescent  tube  igniter  is  by  far  the  best  adapted 
both  for  oil  and  gas  engines,  and  now  that  simple  lamps  have 
been  produced  to  give  a  smokeless  flame  the  incandescent  tube 
is  bound  to  displace  all  other  forms  of  ignition  for  oil  engines. 
The  type  of  lamp  referred  to  also  seems  to  the  author  to  be  the 
best  yet  proposed,  as  it  gives  a  powerful  smokeless  flame  from 
heavy  oils,  and  that  without  the  use  of  the  troublesome  air  blast. 
In  many  of  the  earlier  forms  of  the  engines  described,  an  air 
blast  was  used  somewhat  in  the  manner  shown  at  fig.  194  and 
described  as  the  Griffin  oil  sprayer  lamp.  So  far,  then,  as  the 
present  engine  is  concerned,  the  difficulty  of  igniting  may  be  con- 
sidered as  thoroughly  overcome  in  a  manner  which  is  not  likely  to 
be  greatly  improved  upon,  and  so  far  as  the  ignition  is  concerned 
there  is  nothing  which  prevents  greater  economy  from  being 
obtained.  The  difficulties  which  prevent  immediate  improvement 
in  economy  are  to  be  found  in  all  cases  in  the  methods  of  vapo- 
rising. Some  inventors  claim  to  gasify  wholly  or  partly  the  oil 
which  is  sent  into  the  engine  cylinder,  and  others  claim  that  the 
oil  so  sent  in  is  merely  vaporised  and  not  gasified.  The  author 
has  examined  all  the  standard  types  of  oil  engine  now  in  use,  and 
from  his  own  experiments  he  is  convinced  that  in  not  one  of  the 
engines  does  any  real  gasification  take  place  ;  in  all  the  thirteen 
engines  referred  to  the  oil  is  vaporised,  not  gasified.  In  some  of 


464  Oil  Engines 

the  engines  the  oil  may  be  '  cracked '  to  a  small  extent,  so  that 
the  vapours  produced  are  those  of  lighter  hydrocarbons  than  were 
present  in  the  original  oil,  but  no  cracking  which  can  take  place 
in  any  of  these  engines  is  anything  like  sufficient  to  carry  decom- 
position far  enough  to  produce  gas  instead  of  vapour. 

These  engines  have  been  classified  by  reference  to  the  method 
of  vaporisation  peculiar  to  each,  and  each  type,  although  it 
presents  a  satisfactory  solution  of  the  vaporising  difficulty,  in- 
volves additions  to  the  ordinary  gas  engine  cycle  which  are 
accompanied  by  characteristic  limitations  or  disadvantages. 
Thus  the  first  type  of  oil  engine  using  safe  oil,  'engines  in 
which  the  oil  is  subjected  to  a  spraying  operation  before 
vaporising,'  is  also  first  in  the  order  of  invention,  and  it  naturally 
presents  the  most  complex  solution  of  the  vaporising  difficulty. 
In  this  type  of  engine,  represented  by  the  engines  of  Messrs. 
Priestman  and  Samuelson,  the  whole  air  supply  of  the  engine  is 
passed  through  a  heated  chamber,  and  according  to  Professor 
Unwin,  in  one  of  his  tests,  the  air  leaving  this  heated  chamber 
before  it  enters  the  engine  cylinder  is  raised  to  a  temperature  of 
287°  F.  The  chamber  is  heated  by  the  exhaust  gases  from  the 
engine,  which  gases  in  this  experiment  were  at  a  temperature  of 
600°  F.  ;  the  oil  to  be  vaporised  is  injected  into  the  heating 
chamber,  by  means  of  a  smaller  quantity  of  air,  in  a  state  of  very 
fine  spray,  as  has  been  described  in  the  preceding  chapter.  The 
whole  of  the  oil  used  is  therefore  mixed  with  the  air  passing 
into  the  engine  in  minute  particles  of  spray,  each  of  these  minute 
particles  of  sprayed  oil  being  surrounded  by  an  atmosphere  of  air 
at  a  temperature  of  nearly  290°  F.  Each  oil  particle  thus  has  au 
ample  atmosphere  of  air  surrounding  it  at  this  high  temperature, 
and  thus  each  particle  rapidly  evaporates  and  passes  from  the 
state  of  spray  to  the  state  of  oil  vapour  uniformly  diffused 
throughout  the  air  charge.  The  device  produces  very  perfect 
vaporisation,  but  it  has  the  great  disadvantage  that  the  whole  of 
the  inflammable  charge  entering  the  cylinder  becomes  heated  to 
290°  F.  while  still  at  atmospheric  pressure.  From  this  it  follows 
that  upon  compressing  the  mixture  in  the  cylinder  the  temperature 
of  compression  rises  to  a  much  higher  point  for  a  given  pressure 
than  is  the  case  with  a  gas  engine  charge  working  at  that  pressure. 


The  Difficulties  of  Oil  Engines  465 

In  the  gas  engine  the  charge  enters  the  cylinder  at  atmospheric 
emperature,  and  is  only  heated  to  a  slight  extent  by  the  inclosing 
alls.  In  the  case  of  the  oil  engine  the  entering  charge  is  heated 
o  begin  with,  and  is  likely  to  absorb  further  heat  from  the  piston 
s  it  enters.  This  has  the  effect  of  reducing  the  total  weight  of 
harge  present  in  the  engine  cylinder  at  each  stroke,  and  therefore 
reduces  the  average  available  pressure  to  be  obtained  from  the 
ngine.  In  the  Priestman  engine,  for  example,  the  best  result 
btained  in  Professor  Unwin's  experiments  give  only  a  mean 
vailable  pressure  of  45  Ibs.  per  square  inch  throughout  the  stroke 
ith  a  compression  pressure  of  27  Ibs.  It  is  worth  noting  that  a 
ornpression  pressure  of  27  Ibs.  was  used  in  a  Priestman  engine  at 
time  when  the  usual  compression  pressure  in  gas  engines  ranged 
rom  40  to  50  Ibs.  This  low  pressure  necessarily  involves  less 
conomy  than  the  high  pressure,  and  the  reason  why  a  low  pressure 
adopted  is  found  in  the  fact  that  at  higher  pressures  an  oil  engine 
Derating  by  the  spray  method  is  very  liable  to  premature  ignitions, 
his  is  partly  because  of  the  ready  inflammability  of  a  mixture  of  air 
nd  heavy  oil  vapour,  and  partly  because  of  the  higher  tempera- 
ure  of  compression  due  to  the  preliminary  heating  of  the  whole 
harge  in  the  vaporiser.  An  oil  and  air  charge  is  much  more 
iable  to  spontaneous  ignition  during  compression  than  a  gas  and 
r  charge,  and  the  preliminary  heating  of  the  whole  charge  to 
bout  80°  F.  above  the  boiling  point  of  water  necessarily  increases 
he  temperature  obtained  by  compression,  and  this  higher  tem- 
)erature  tends  to  make  the  charge  ignite  prematurely. 

It  is  interesting  to  note  that  with  Daylight  oil  Professor 
Jnwin  found  a  pressure  of  compression  of  35  Ibs.  per  square  inch 
more  suitable  than  27  Ibs.  This  is  doubtless  due  to  the  fact 
lat  lighter  oils  such  as  Daylight  oil  when  vaporised  approxi- 
late  more  nearly  to  the  gaseous  condition,  and  are  therefore  less 
asily  subject  to  premature  ignition  than  the  heavier  oils. 

One  difficulty,  therefore,  caused  by  the  spray  method  of 
gnition  lies  in  the  limitation  of  the  weight  of  the  charge  by  pre- 
iminary  heating,  from  which  follows  the  production  of  a  lower 
verage  pressure  ;  another  difficulty  lies  in  the  limitation  of  the 
ornpression  pressure  due  to  the  property  of  spontaneous  ignition, 
which  is  made  more  marked  by  the  preliminary  heating.  These 

H  H 


466  Oil  Engines 

difficulties  prevent  the  attainment  of  greater  economy  by  the  first 
method  of  vaporising. 

This  method,  however,  presents  other  difficulties  of  a  practical 
kind.  Thus  a  large  volume  of  charge  is  formed  in  the  vaporiser 
in  explosive  proportions,  and  the  whole  of  this  charge  is  liable  to 
be  ignited  in  the  event  of  a  back  explosion  from  the  engine 
cylinder  while  the  charging  stroke  is  proceeding.  This  is  a 
serious  difficulty,  and  has  caused  in  gas  engines  the  practical 
abandonment  of  all  engines  in  which  a  reservoir  of  gas  and  air 
is  used  to  feed  the  engine  cylinder. 

A  further  difficulty  occurs  in  governing  the  engine.  As  the 
exhaust  gases  are  used  to  heat  the  vaporiser,  by  means  of  a 
jacket  surrounding  the  vaporiser  chamber,  it  follows  that  the 
ordinary  method  of  governing  practised  in  the  gas  engine  is 
inapplicable.  Messrs.  Priestman  accordingly  produce  ignitions 
under  all  circumstances,  whether  their  engine  be  light  or  loaded  ; 
that  is,  instead  of  cutting  out  impulses  by  stopping  off  the  oil 
supply  completely,  they  reduce  both  oil  and  air  supply  simul- 
taneously, and  by  so  doing  reduce  the  pressure  at  which  the 
cylinder  is  filled  with  inflammable  mixture  before  compression 
begins.  The  proportion  of  oil  and  air  admitted  is  kept  as  nearly 
as  possible  constant,  but  the  compression  pressure  is  continuously 
reduced  and  produces  weaker  and  weaker  impulses.  This  is 
clearly  shown  in  the  diagram,  fig.  191,  page  417,  where  the  full-power 
diagram  is  shown  by  a  heavy  black  continuous  line,  the  half- 
power  diagram  by  a  dotted  line,  and  the  diagram  produced  when 
the  engine  is  running  light  by  a  thin  full  line.  This  method  is  by 
no  means  an  economical  one,  and  results  in  a  heavy  consumption 
of  oil  even  at  light  loads.  In  Professor  Unwin's  test,  for  example, 
it  was  found  that  the  engine  consumed  6|  Ibs.  to  7  Ibs.  of  oil  per 
hour  when  working  at  full  power ;  and  when  working  giving  no 
power  at  all,  only  driving  itself  at  full  speed,  the  oil  consumption 
was  still  5  Ibs.  This  of  course  is  a  very  poor  result,  the  engine 
using  almost  as  much  oil  without  load  as  at  full  load  ;  in  fact  in 
Unwin's  test  there  was  no  difference  in  oil  consumption  between 
half  power  and  no  load  at  all.  This  is  a  difficulty,  however, 
which  is  common  to  all  gas  engines  as  well  as  oil  engines  in  which 
the  charge  is  supplied  from  an  intermediate  reservoir  of  consider- 


The  Difficulties  of  Oil  Engines  467 

j  able  capacity.  With  such  a  reservoir  it  is  evident  that  the  govern- 
ing cannot  be  effected  by  simply  cutting  off  the  gas  supply,  as 
if  the  governor  had  acted  the  engine  would  still  receive  one  or 
more  charges  and  give  one  or  more  impulses  after  the  governor 
had  signalled  that  it  was  running  too  fast.  In  the  same  way, 
when  the  governor  put  the  gas  or  oil  supply  on  fully  again,  the 
engine  had  to  make  several  revolutions  before  the  mixture  reached 
the  cylinder.  This  causes  serious  irregularity  as  well  as  loss  of 
gas  due  to  imperfect  mixture  at  the  time  of  governing. 

Messrs.  Samuelson  endeavour  to  avoid  this  difficulty  of  governing 
by  holding  closed  the  exhaust  valve,  and.  keeping  the  inlet  valve 
closed.  In  this  way  the  piston  expands  and  compresses  the  ex- 
haust gases  without  taking  any  charge  from  the  vaporiser.  This 
method  of  governing,  however,  is  not  satisfactory,  because  of  the 
difficulty  of  keeping  a  constant  charge  in  the  vaporiser  while 
the  engine  is  governing.  A  further  difficulty  is  due  to  the  fact 
that  when  the  explosions  cease  exhaust  gases  no  longer  pass 
round  the  vaporiser,  and  the  temperature  rapidly  falls,  so  that  it  is 
liable  to  get  much  too  cool  for  the  effective  performance  of  its 
work.  This  difficulty  affects  the  Priestman  engine  to  a  lesser 
extent  because  of  the  continuance  of  the  explosions,  but  even 
there  the  temperature  of  the  vaporiser  falls  considerably  when 
the  engine  is  running  with  light  loads  or  no  load  at  all. 

In  the  author's  opinion  the  spray  method  of  vaporising  as 
hitherto  carried  out  is  the  least  satisfactory  of  all  the  methods  of 
vaporising,  and  the  second  and  third  methods  present  consider- 
able advantages  over  it,  both  in  simplicity  and  effective  operation. 

The  second  type  of  oil  engine  comprises  '  engines  in  which 
the  oil  is  injected  into  the  cylinder  and  vaporised  within  the 
cylinder.'  The  engines  constructed  under  this  type  repre- 
sented by  the  Hornsby,  the  Robey,  and  the  Capitaine  engines, 
distinctly  advance  upon  the  spray  method  of  vaporising,  but  they 
also  present  difficulties  of  a  somewhat  formidable  kind.  The 
Hornsby- Ackroyd  engine,  for  example,  tested  at  the  Royal  Agri- 
cultural Society's  Show  gave  a  mean  available  pressure  throughout 
the  stroke  of  only  29  Ibs.  per  sq.  in.  This  of  course  necessitates  a 
large  cylinder  for  a  given  power.  The  mean  pressure,  it  will  be 
observed^  is  lower  than  that  given  by  Class  I.,  and  this  although 

H  H  2 


468  Oil  Engines 

the  compression  pressure  is  much  higher.  The  Hornsby  engine 
gave  a  compression  pressure  of  50  Ibs.  per  sq.  in,  and  should  have 
given  a  higher  average  pressure  than  that  of  Class  I.  but  for 
certain  peculiarities  which  have  now  to  be  considered.  In  this 
type  of  engine  the  walls  of  the  combustion  space  are  allowed  to 
attain  a  temperature  of  nearly  800°  C.,  sufficient  to  cause  effective 
vaporisation  and  also  to  allow  of  ignition  when  compression  is 
completed.  The  air  charge  entering  the  cylinder  in  the  Hornsby 
engine  does  not  pass  through  the  combustion  space,  but  passes 
directly  into  the  water-jacketed  cylinder.  The  air,  therefore,  is 
not  heated  up  by  passing  through  the  vaporising  chamber  ;  the 
exhaust  gases  of  the  previous  explosion,  however,  are  kept  at  a  very 
high  temperature  in  the  combustion  chamber,  which  chamber 
is  cut  off  to  a  certain  extent  from  the  main  cylinder  by  the 
bottle  neck  seen  at  fig.  195,  page  421.  The  cause  of  the  low 
available  pressure,  however,  is  not  due  to  heating  of  the  air  while 
entering,  the  cylinder,  as  that  heating  only  occurs  to  a  slightly 
greater  extent  than  in  the  case  of  the  gas  engine.  The  real  cause 
of  the  low  average  pressure  is  imperfect  mixing  of  the  air  charge 
with  the  oil  vapour.  The  oil  is  injected  into  the  combustion 
space  A  during  the  charging  stroke  of  the  piston.  It  rapidly 
evaporates  because  of  its  contact  with  the  highly  heated  walls, 
and  it  diffuses  among  the  hot  exhaust  gases  contained  in  the 
combustion  space.  As  there  is,  however,  very  little  oxygen  pre- 
sent in  that  space  at  the  moment  of  vaporising,  there  is  no  danger 
of  premature  ignition.  Ignition  is  not  possible  until  air  has  been 
forced  from  the  cylinder  through  the  bottle  neck  to  supply 
oxygen  sufficient  for  the  combustion  of  the  vaporised  oil.  As  the 
compression  proceeds,  more  and  more  air  mixes  with  the  vapo- 
rised oil,  and  sufficient  oxygen  is  forced  .into  the  combustion 
chamber  to  properly  burn  the  oil  vapour  charge.  A  certain 
amount  of  oxygen,  however,  and  nitrogen  remains  outside  the 
combustion  chamber  in  the  space  between  its  limits  and  the 
piston,  and  so  the  cylinder  is  not  filled  with  a  uniform  inflan> 
mable  mixture.  The  mixture  produced  within  the  combustion 
chamber  is  also  less  perfectly  mixed  with  the  air  than  the  charge 
in  a  gas  engine  cylinder,  and  accordingly  to  insure  complete  com-i 
bustion  of  the  whole  charge,  a  much  larger  proportion  of  oxygen 


The  Difficulties  of  Oil  Engines  469 

is  necessary  than  in  the  gas  engine.  The  average  pressure  of  the 
explosion  is  thus  considerably  reduced. 

The  reduction  of  average  pressure  would  not  matter  much  if 
the  only  requirement  were  a  larger  diameter  of  cylinder ;  that  is,  an 
increased  diameter  without  corresponding  increase  of  the  strength 
of  the  crank,  connecting  rod,  and  engine  frame  ;  unfortunately, 
however,  in  the  case  of  an  oil  engine  or  a  gas  engine  the  effect  of 
a  double  charge  has  always  to  be  well  kept  in  mind.  Such  a 
double  charge  would  raise  the  maximum  pressure  to  an  unsafe 
point  for  a  given  diameter  of  cylinder  unless  the  parts  were  made 
sufficiently  strong  to  resist  this  possible  contingency.  In  the  oil 
engine,  for  example,  an  explosion  might  be  missed  and  a  double 
charge  of  oil  vapour  would  be  left  in  the  cylinder,  and  so  the  maxi- 
mum pressure  of  the  next  explosion  greatly  increased.  Engines 
of  Class  II.  have,  therefore,  large  cylinders  and  heavy  parts  in  pro- 
portion to  the  power  developed  by  them.  Their  economy  also  is 
not  proportional  to  the  compression  pressures  used. 

The  governing  difficulty  is  also  much  felt  in  this  type  of 
engine.  Here  it  is  possible  to  stop  the  oil  supply  and  cut  out 
explosions  just  as  in  the  case  of  a  gas  engine,  but  the  effect  of  this 
is  to  cause  the  walls  of  the  combustion  space  to  be  rapidly  cooled 
down  at  light  loads.  Most  of  the  engines  of  this  kind  work  well 
at  full  or  intermediate  loads,  but  at  light  loads  the  combustion 
space  walls  may  become  so  cool  that  ignition  fails  and  the  engine 
stops.  Messrs.  Hornsby  have  got  over  this  difficulty  to  a  very 
great  extent,  but  it  is  a  difficulty  which  is  quite  formidable  in  this 
type  of  engine.  If  the  combustion  chamber  be  so  arranged  and 
shaped  that  its  walls  are  sufficiently  hot  when  the  engine  is  running 
without  load,  they  are  very  apt  to  be  overheated  at  full  loads. 
The  skill  of  the  makers  of  these  engines  is  well  shown  in  pro- 
portions calculated  to  keep  the  combustion  space  walls  hot,  and 
yet  not  too  hot. 

The  fundamental  idea  of  this  type  of  engine  is  extremely 
fascinating  and  simple,  but  considerable  complexities  arise  in 
carrying  it  into  effect,  which  greatly  detract  from  the  advantages. 

In  the  author's  opinion  this  type  of  engine  will  always  be 
somewhat  heavy  and  large  for  the  power  developed,  as  it  is 
difficult  to  see  how  greater  average  pressures  are  to  be  obtained, 


470  Oil  Engines 

or  how  greater  economies  are  to  be  expected  by  reason  of  any 
modifications  of  the  type. 

The  third  type  of  oil  engine  comprises  '  engines  in  which  the 
oil  is  vaporised  in  a  device  external  to  the  cylinder,  and  intro- 
duced into  the  cylinder  in  a  state  of  vapour.'  Engines  of  this 
class,  in  the  author's  opinion,  furnish  the  simplest  and  most  effec- 
tive solution  of  the  problems  involved  in  oil  engine  construction. 
Even  this  class,  however,  presents  two  divisions.  The  first 
division  includes  the  engines  of  Messrs.  Crossley  Brothers,  and 
Fielding  &  Platt.  In  these  engines  oil  is  injected  into  a  heated 
vaporiser  consisting  of  eicher  a  series  of  tubes  or  a  series  of 
tubular  passages.  These  tubes  or  passages  are  heated  by  the 
waste  heat  of  the  oil  lamp  used  for  the  incandescent  tube.  The 
oil  is  injected  at  one  end  of  the  series  of  passages  together  with  a 
small  quantity  of  air,  and  a  small  further  quantity  of  air  is  heated 
up  by  an  air  heater  before  reaching  the  oil ;  this  hot  air  passes 
through  the  vaporiser  part  of  the  tubes,  and  evaporates  the  oil 
and  carries  a  charge  into  the  engine  cylinder  in  a  state  of 
vapour.  The  main  air  charge  enters  the  cylinder  by  a  separate 
valve,  so  that  only  a  very  small  part  of  the  air  charge  is  heated 
and  passed  in  with  the  oil.  By  this  arrangement  the  engine 
cylinder  itself  and  all  the  surfaces  in  contact  with  the  charge 
are  water-jacketed,  just  as  in  the  case  of  the  gas  engine.  The 
oil  vapour  and  heated  air  entering  at  a  port  mix  with  the 
cold  air  entering  at  a  separate  valve,  and  no  doubt  some 
little  precipitation  of  the  oil  vapour  will  occur  because  of 
the  cold  air  impinging  upon  the  hot  air  saturated  with  in- 
flammable vapour.  This  precipitation,  however,  will  be  in  the 
state  of  very  fine  mist  indeed,  and  on  the  compression  of  the 
charge  the  rising  temperature  of  compression  will  speedily  cause 
the  vapour  to  be  formed  again.  This  method  of  vaporising  has 
the  advantage  that  the  air  charge  is  heated  up  to  the  smallest 
possible  extent  consistent  with  forming  an  explosive  charge  by 
means  of  heavy  oil.  The  compression  can  thus  be  increased  to  a 
greater  extent  than  in  the  first  two  classes  without  danger  of 
premature  ignition,  and  so  much  higher  average  pressures  are 
rendered  possible.  Accordingly  we  expect  to  find  a  higher 
average  pressure  in  this  engine  than  in  the  others.  Messrs. 


The  Difficulties  of  Oil  Engines  471 

Crossley  obtained  72  Ibs.  per  sq.  in.  mean  pressure  with  an  ex- 
plosion pressure  of  225  Ibs.  and  a  compression  pressure  of  65  Ibs., 
while  Messrs.  Fielding  &  Platt  obtain  a  mean  pressure  of  63  Ibs. 
with  a  compression  pressure  of  40  Ibs.  This  method  of  operation 
also  has  the  advantage  that  it  allows  of  the  usual  gas  engine  mode 
of  governing,  viz.  by  cutting  out  explosions.  That  the  governing 
is  effective  and  economical  is  seen  from  the  fact  that  a  Crossley 
engine  which  used  9-9  Ibs.  of  Russoline  oil  per  hour,  running 
at  full  load,  only  used  2-53  Ibs.  per  hour  running  at  full  speed 
without  load,  both  figures  including  the  oil  for  operating  the 
heating  lamp.  The  Crossley  engine  tested  was  rated  at  7^  HP. 
A  3-horse  engine  tested  by  Messrs.  Fielding  &  Platt,  which  con- 
sumed 475  IDS-  of  Russoline  oil  per  hour  at  full  load,  ran  without 
load  on  i  -3  Ib.  per  hour.  These  results  show  governing  almost  if 
not  quite  presenting  the  same  proportional  economy  as  a  gas 
engine. 

The  second  division  includes  the  engines  of  Messrs.  Tangye, 
Campbell,  the  Britannia  Co.,  Clarke,  Chapman  &  Co.,  Weyman 
&  Hitchcock,  and  Wells  Bros.,  and  in  these  engines  in  all  cases 
except  one  (Clarke,  Chapman  &  Co.)  the  whole  air  charge  of  the 
engine  passes  through  the  vaporiser  on  its  way  to  the  cylinder. 
This  method  of  operating  as  carried  out  by  Messrs.  Tangye  and 
Campbell  has  certainly  the  advantage  of  great  simplicity,  but  it 
appears  to  have  a  disadvantage  of  less  perfect  vaporisation  than 
is  given  in  the  first  division.  At  least  a  comparison  of  the  oil 
consumption  of  the  different  engines  seems  to  point  to  this.  For 
instance  the  Crossley  and  Fielding  &  Platt's  oil  engines  respec- 
tively consume  '82  and  -90  Ib.  of  Russoline  oil  per  BHP  hour, 
while  the  Campbell,  Britannia,  Wells,  Weyman  &  Hitchcock 
engines  consume  respectively  ri2,  1*68,  1-04,  and  1-19  Ib.  of 
oil  per  BHP  hour.  The^  engines  of  the  second  division  thus 
consume  uniformly  more  oil  per  BHP  hour  than  those  of  the  first 
division. 

In  the  author's  opinion  this  is  partly  caused  by  the  fact  that 
the  whole  air  charge  is  drawn  through  the  vaporiser,  and  partly 
by  the  fact  that  in  all  of  these  engines  the  explosion  pressure  has 
free  access  to  the  vaporiser  up  to  the  inlet  valve.  By  drawing 
the  whole  of  the  air  charge  through  a  vaporiser  with  no  prelimi- 


472  Oil  Engines 

nary  heating  or  only  a  slight  preliminary  heating,  the  temperature 
of  the  air  is  so  low  that  it  does  not  assist  in  any  way  the  vaporising 
of  the  charge,  but  rather  retards  it.  As  pointed  out  in  Chapter  I. 
of  this  Part  of  the  book,  air  can  only  take  up  oil  vapour  suffi- 
ciently to  saturate  it  at  the  particular  temperature  of  the  air  ;  and  as 
the  tension  of  oil  vapour  is  very  low  at  the  temperature  of  the 
atmosphere,  the  air  dees  not  really  help  in  vaporising,  but 
rather  tends  to  condense  the  vapour  formed  by  the  hot  walls  of 
the  vaporiser.  The  oil,  therefore,  which  is  taken  into  the 
cylinder  is  taken  in  partly  as  vapour  and  largely  as  a  somewhat 
heavy  spray.  This  heavy  spray  readily  falls  on  to  the  walls  of  the 
cylinder  and  produces  a  less  perfect  charge. 

The  fact  of  keeping  the  vaporiser  open  to  the  explosion 
right  up  to  the  inlet  valve  has  the  same  effect  in  an  oil  engine  as 
it  would  have  in  a  gas  engine ;  that  is,  it  increases  the  port  sur- 
faces so  much  as  to  seriously  cool  the  flame  of  the  explosion 
when  the  explosion  occurs.  These  two  causes  are,  in  the  author's 
opinion,  the  principal  causes  of  the  higher  consumption  of  the 
second  division  of  this  class. 

To  make  this  type  of  vaporiser  effective  the  air  would  require 
to  be  heated  to  a  considerable  temperature  before  entering  the 
vaporiser,  and  this  would  of  course  introduce  the  difficulties 
which  have  been  already  referred  to  in  discussing  Class  I.  A 
valve,  it  is  true,  might  be  placed  between  the  explosion  port  and 
the  tubular  or  passage  port  of  the  vaporiser,  and  this  would  un- 
doubtedly improve  the  economy  while  running  loaded,  but  it 
would  also  increase  the  difficulty  of  effective  governing.  This 
type  of  engine  as  described  is  readily  governed,  and  very  high 
economies  are  obtained  running  without  load.  To  make  the 
comparison  more  readily  evident,  the  author  has  prepared  the 
table  on  page  473,  which  contrasts  the  leading  facts  connected 
with  the  three  classes  of  engine. 

Oil  Engine  Improvements. — The  reader  must  not  suppose  that 
in  the  preceding  discussion  the  author  is  in  any  way  under- 
valuing the  great  progress  which  has  been  made  in  oil  engine 
construction.  Greater  improvements  are  to  be  made  in  oil 
engines  than  in  gas  engines,  but  inventors  are  rapidly  overcoming 
all  the  difficulties,  and  the  oil  engine  of  to-day  is  a  very  effective 


The  Difficulties  of  Oil  Engines 

COMPARISON  OF  OIL  ENGINES. 


473 


CLASS  I. 

CLASS  II. 

'CLASS  III 
-  Div.  I. 

CLASS 
Div.  I 

III. 
I. 

Oil  consumption  ) 
per  BHP  hour  j 

•95  lb. 

•98  lb. 

•82  lb. 

i'i2lb. 

1-68  lb. 

i  '04  lb. 

i  '19  lb. 

Oil  consumption  ) 
per  1HP  hour   \ 

•86  lb. 

•81  lb. 

•73  lb. 

•93  lb. 

1-25  lb. 

o'93  lb. 

•87  lb. 

Mean  available  1 
pressure  .         .  J 

45  lb. 

29  lb. 

72  lb. 

65-5  lb. 

47'3  lb. 

49'61b. 

46-1  lb. 

Explosion  pressure 

130  lb. 

112  lb. 

225  lb. 

200  lb. 

i55  lb. 

135  lb. 

145  lb. 

Compression        \ 
pres>ure  .         .  J 

27  lb. 

50  lb. 

65  lb. 

40  lb. 

45  lb. 

32  lb. 

38  lb. 

Power  of  engine 

7  BHP 

8  BHP 

7iBHP 

4'8  BHP 

6-2  BHP 

6-5  BHP 

4-7  BHP 

Name  of  maker  . 

Priestman 

Hornsby 

Crossley 

Campbell 

Britannia  Co. 

Wells 

Weyman 

Weight       . 

36  cwt. 

40  cwt. 

Z-z\  cwt. 

27  cwt. 

33  cwt. 

36^  cwt. 

26  cwt. 

and  reliable  machine.  It  is  idle  to  deny,  however,  that  further 
improvements  are  possible,  and  the  author's  object  is  to  point  out 
the  difficulties  as  clearly  as  possible  in  order  to  aid  inventors  in 
working  on  correct  lines.  Improvements  in  vaporisers  will  pro- 
bably take  the  form  of  obtaining  a  very  complete  cracking  of  the 
oil,  tending  to  charge  the  cylinder  with  vapours  of  lighter  oils 
than  those  introduced  into  the  vaporiser.  This  process  will 
supply  the  engine  with  oils  capable  of  withstanding  higher  com- 
pressions than  are  at  present  used  without  premature  ignitions. 
Every  effort  will  be  made  also  to  keep  all  parts  of  the  cylinder 
cool  and  water-jacketed  as  with  the  gas  engine.  The  heating 
lamp  is  also  capable  of  improvement,  and  efforts  should  be  made 
to  produce  a  flame  of  the  Bunsen  or  smokeless  type,  giving  less 
noise  than  at  present.  Oil  engine  inventors  will  pay  more  atten- 
tion to  the  now  well-understood  principles  of  gas  engine  design, 
and  will  accordingly  do  away  as  much  as  possible  with  all  long 
ports  or  increased  surfaces  in  contact  with  the  flame  of  the 
explosion. 


APPENDIX   I 


ADIABATIC  AND  ISOTHERMAL  COMPRESSION  OF  DRY  AIR. 
(Professor  R.  H.  Thurston,  Journal  of  Franklin  Institute,  1884.) 

One  hundred  volumes  of  dry  air  at  the  atmospheric  mean  temperature 
of  15*5°  C.  and  147  Ibs.  per  square  inch  undergo  change  of  volume 
without  loss  or  gain  of  heat.  The  temperatures  and  volumes  corre- 
sponding to  various  pressures  are  given.  Also  the  volumes  at  the 
various  pressures  if  the  temperature  remained  constant  at  15-5°  C. 


Absolute  pressure  in 
Ibs.  per  sq.  inch 

Temperature  of 
compression  in 
Centigrade  degrees 

Volume  at 
temperature  and 
pressures  preceding 

Volume  if 
temperature  constant 
at  15-5° 

J4'7 

IS'5 

lOO'O 

17*26 

98-58 

98-00 

20*0 

42*60 

80*36 

73-50 

25-0 

64*76 

68*59 

58-80 

30*0 

82*10 

60*27 

4900 

35  'o 

98*38 

54  'oi 

42*00 

40*0 

113*86 

49"I3 

3°  "75 

45  'o 

126*54 

45'i8 

3^*67 

50-0 

138*96 

4I-93 

29*40 

55  'o 

15°  '53 

39-I9 

26*73 

* 

60*0 

161*38 

36*84 

24*50 

°5  '° 

171*61 

34*80 

22*02 

70*0 

181*29 

33'02 

21-00 

80-0 

190*49 
199*26 

3  1  '44 
30-03 

19*60 
18-38 

85-0 

207  *66 

28*77 

17*29 

90*0 
95  'o 

100  -0 

125-0 
150-0 

175  '0 

214*71 

223-45 
230-91 
264-66 
293-91 

27*62 
26*58 

25-63 
21-88 
19*22 
17*23 

I6-33 
15-47 
1470 
11-76 

9'8o 
8-40 

200-0 

343-3! 

r5  67 

7/35 

225-0 
250*0 

364*71 
4"  "57 

14*41 
13-38 

300-0 
4OO'O 

420*34 
480*76 

ii-75 

4-90 
3'9o 

5OO*O 
600*0 

53i'21 
574  '93 

8*17 
7*18 

2-94 
245 

700*0 
800*0 

603*74 
648*80 

6*44 
5  '86 

2'IO 
I-84 

9OO'O 

680*86 

5'39 

1-63 

1000 
2000 

710*49 
929-67 

5-00 
3-06 

1-47 

0*74 

476 


The  Gas  Engine 


ANALYSIS  OF  COAL  GAS. 
(T.  Chandler,    Watts'  'Diet.'  Supp.  3,  Part  i.) 


Heidelberg 

Bonn 

Chemnitz 

London 

Ordinary 

Cannel 

coal  gas 

gas 

vols. 

vols. 

vols. 

vols. 

vols. 

Hydrogen,  H       .     . 

44-00 

39-80 

51-29 

46-00 

2770 

Marsh  gas,  CH4  . 

38-40 

43'12 

36'45 

39  '50 

50-00 

Carbonic  oxide,  CO  • 

573 

4-66 

4  '45 

7  '5° 

6-80 

Heavy  hydrocarbons 

7-27 

475 

4-91 

3-80 

I3'OO 

Nitrogen,  N    .     .     . 

4'23 

4-65 

1-41 

°'5° 

0'40 

Carbonic  acid,  COo  . 

0-37 

3-02 

i  -08 

— 

O'lO 

Water  vapour,  H.>O  . 

— 

2  '00 

2  '00 

ANALYSIS  OF  LONDON  COAL  GAS. 

(Hvmp'dge.} 


Sample  (A) 

Sample  (B) 

Hydrogen,  H     . 
Marsh  gas,  CH4         ..... 
Carbonic  oxide,  CO  
Olefines     
Nitrogen,  N       ...... 
Carbonic  acid,  CO.2   

vols. 

50  '05 
32-87 

12-89 

3'£7 
0-32 

vols. 
51  "24 
35'28 
7-40 
3'5* 

2  24 
0-38 

ANALYSIS  OF  BERLIN  AND  NEW  YORK  COAL  GAS. 


Berlin 

New  York  Municipal 
Gas  Light  Co. 

vols. 

vols. 

Hydrogen,  H 

4975 

3°  '30 

Marsh  gas,  CH4 
Carbonic  oxide,  CO 
Ethvlene,  C2H4    . 

32-70 

o'54 
4-61 

24-30 
26-50 

I  TOO 

Nitrogen,  N 

0-68 

2*40 

Carbonic  acid,  COo      .         .         . 

2-50 

I'OO 

Oxygen,  O  . 

0'22 

0-50 

Appendix  I 


'477 


ANALYSIS  OF  NATURAL  GAS  FROM  GAS  WELLS  IN  PENNSYLVANIA. 
(  Watts'  '  Diet,  of  Chemistry, '  Supp.  3,  Part  2. ) 


Burns  Butler 
Co.'s  well 

Lechburgh 
Westmoreland  Co. 

Harvey 
Butler  Co. 

vols.                            vols. 

vols. 

Carbonic  acid,  CO> 

034 

°'35 

0'66 

Carbonic  oxide,  CO 

trace 

0'26 



Hydrogen,  H 

6'IO 

479 

1  3  '50 

Marsh  gas,  CH4   . 

75  '44 

89-65 

80-11 

Ethylene,  C2H4    . 
Hydrocarbons      composition 

18-12 

4  '39 

572 

not  stated  .... 

— 

0-56 

~~ 

478 


The  Gas  Engine 


1- 

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5^  C0  .0  w^  C4  vo  Ct.  d  tx  m        -^-o^-  o^^O   tx  0      m     uS  N 
N   0   O   t~Cs  'in'cxvb  W       Vw  W'm'ro'ro    V    VYo 

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Appendix  II 


479 


v? 

M 

C/5 

ftfflJl 

to  1,980,000 
foot-lbs.,  or 
i  HP  for  one 
hour 

CO 
HOI   -J-vQ    ONVO    H   ON  CO 
01  VO  vO    O  CO    LOVO    H 
CO  LO  tx  txvp    JO  p    tx 

CO  CO  CO  CO  CO  CO  CO  CO  'rl-  CO 

LO  LO  -t-  covo  M  oi  co  rx  tx 
<?,  H"  ONCp°  M5  O  "p   M5  O*  ON 

O 

fa 

( 

^-      Cx  LOCO    "^j"  tx  CO    w    LOVO  vO 

5|8|^<|tg>| 

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to 
W 
J 

1 

0 

°- 

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£     VO    LO  LO  LO  LO  VO  LO  LO^-  LO 

8^?^^^%c?& 

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VO    "^vO  vO    r}-  LO  'O  w    rj-  LO 

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5 
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ANALYST 

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1000    }O  ^vO    H    JO  CO  Tf  IO 

01  CO    Vf  CM    rf  fx  OJ    O    ON  O 
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cocococococococococo 

WJ 

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55 

8  j!~.1:f).Q 

11 

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HI    CxOO  vO    tx  Cx  CO  O    O    CO 
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LOOICO  o  cocococo  ONOO 

COvO  vO    tx  LO  IOVO    LO  O  CO 
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480 


The  Gas  Engine 


TABLE  III.  CALCULATED  FROM  TABLE  I. 

Oxygen  or  air  required  for  complete  combustion  of  i  vol.  of  each  of  the 
following  gases. 


Town 

Oxygen 

Air 

Vol.  of  products 

vols. 

vols. 

Edinburgh        .                  .'        . 

•55 

7-40 

8-25 

Glasgow  .                           . 

•44 

6-85 

7-65 

St.  Andrews 

•49 

7-08 

7-88 

Liverpool 

'37 

6-52 

5  '45 

Preston    . 

•28 

6'io 

6'88 

Nottingham 

'3° 

6-17 

6-14 

Leeds       . 

•40 

667 

7  '47 

Sheffield  . 

•35 

6-49 

7-28 

Birmingham 

•09 

5*19 

6-08 

Bristol      . 

•29 

6'i6 

6  '95 

London  — 

Gaslight  &  Coke  Co.       . 

•20 

576 

6'53 

South  Metropolitan  Co. 

-I5 

5  '47 

6  '20 

Redhill     

•22 

5'32 

6-58 

Gloucester        .... 

>25 

5  '94 

6-69 

Newcastle-on-Tyne  . 
Newcastle-under-Lyme    . 

•i5 
•20 

5-49 
572 

6-24 
6-48 

Brighton  

•18 

5-62 

6-36 

Southampton   .... 

•17 

5-56 

6  '29 

Ipswich    ..... 

•18 

5-63 

6-31 

•18 

S'6? 

6'^Q 

O      -J 

w  jy 

LIST  OF  BRITISH  GAS  AND   OIL  ENGINE 
PATENTS 

Frcm  the  year  1791  to  1893  inclusive. 
1791. 

NO. 

J833.     John  Barber. — Using  inflammable  air  for  the  purpose  of  producing 
motion. 

1794. 

1983.     Robert  Street. — Method  of  producing  an  inflammable  vapour  force  by 
means  of  fire,  flame,  &c. 

1797. 

2164.     James  Glazebrook. — Working  machinery  by  means  of  the  properties 
of  air. 

1801. 

2504.     James  Glazebrook. — Po\ver  from  mixtures  of  air,  such  as  hydrogen, 
nitrous  air,  £c. 

1817. 
4179.     J.  C.  Niepce. — Propelling  vessels  by  explosive  gases. 

1823. 

4874.     Samuel  Brown. — Effecting  a  vacuum   by  flame,  and  thus  producing 
power. 

1826. 

5350.     Samuel  Brown. — Improvements  in  his  former  patent,  No.  4874. 
5402.     E.   Hazard. — Preparing  mixtures  of  vapours  with  air,  and  exploding 
them  to  obtain  motive  power. 

1833- 

6525.     L.  W.  Wright. — Explosive  engine.    Carburetted  hydrogen  and  air  are 
forced  into  reservoir  and  exploded. 

I  I 


482  The  Gas  Engine 

1835- 

6875.  J.  C.  Douglass.  — Explosion  engine. 

1838. 
7615.  W.    Barnett. — Obtaining   motive  power    from    inflammable  gases  by 

compression  and  explosion. 

7871.   Byerley  &  Collins. — Using  of  steam  or  gas,  or  both  combined,  with     : 
the  hydrostatic  paradox. 

1839. 
8207.   H.  Pinkus. — Motive  power  obtained  either  by  explosion  or  exhaustion. 

1840. 
8644.   Henry  Pinkus.— Explosion  engine. 

1841. 

8841.  James  Johnson. — Motive  power  obtained  by  the  explosion  of  oxygen 
and  hydrogen. 

1843- 
9972.  Joseph  Robinson. — Engine  driven  by  inflammable  gas  or  vapour. 

1844. 

10404.  J.  W.  B.  Reynolds. — Gas  or  pneumatic  locomotive  engines  ;  explosion 
of  a  mixture  of  gas  and  air. 

1846. 
11072.  Samuel  Brown. — Improvements  in  gas  engines  and  in  propelling  car-  I 

riages  and  vessels  (no  specification  enrolled). 

11245.  W.  Cormack. — Motive  power  is  obtained  by  contraction    and    rare- 
faction. 

1850. 
13302.  E.  C.  Shepard. — Explosion  engine. 

1852. 

940.   N.  Seward. — Motive  power.     Gunpowder. 

979.  W.  Quaterman  (provisional  only).— Motive  power  by  gaseous  matter. 
14086.   Samuel  Haseltine. — Improvements  in  engines  to  be  worked  by  air  or 

gases  (no  specification  enrolled). 
14150.  A.  V.  Newton. — Gas  engine. 

1853- 

362.   Robert   Roger  (provisional  only).— Obtaining   motive  power   by  ex- 
plosion. 
515.  R.  L.  Bolton.  —Motive  power  is  obtained  from  the  explosion  of  gases. 


Appendix  II  483 

NO. 

1248.     E.  J.  Schollick. — Water  is  decomposed  by  electric  currents  into  its 
component  gases,  which  gases  pass  into  a  cylinder,  and  are  exploded 
.   by  another  electric  apparatus. 

1577.     Joseph   Webb   (provisional    only). — Improvements  in  obtaining   and 
applying  motive  powers  (gas  and  electricity)  by  explosion. 

1648.     Fabian  Wrede Improvements  in  gas  and  air  engines. 

1671,     A.    Carosio  (provisional    only). —  Producing  explosive    gases    electro- 
magnetically. 

1854. 
191.     James  Anderson  (provisional  only) — Motive  power  obtained  by  air, 

gases,  or  vapour. 
549.     J.  C.  Edington  (provisional  only) — Mixture  of  carburetted  hydrogen 

and  air,  exploded  in  a  cylinder. 

1072.     Barsanti  &   Matteucci    (provisional    only).— Apply    the    explosion  of 
gases  as  a  motive  power  (atmospheric  engine). 

1855- 

3^9.     T.  B.  Blanchard. — Motive  power  from  combustion. 
562.     Alfred  V.  Newton. — Improvements  in  engines   worked  by   explosive 

mixtures. 

ion.     Henri    Balestrino    (provisional    only) — Improvements    in    obtaining 
motive  power  by  aid  of  explosive  gases. 

1856. 

1807.     C.  J.  B.  Torassa. — Improvements  in  obtaining  motive  power  by  aid 
of  explosive  gases. 


1655.     Barsanti   &    Matteucci.— Improvements   in   obtaining    motive   power 

from  explosive  gases. 
1754.     J.  S.  Rousselot Improved  method  for  obtaining  motive  power,  and 

engme  for  applying  the  same. 
2408.     J.  E.  F.  Luedeke.— Motive-power  engine  (explosion). 

1858. 

969.     W.  Clark. — Burnt  air  motor. 

996.     C.  D.  Archibald Treating  air  or  gases  for  purposes  of  motive  power.' 

2648.     R.  Nelson. —Vacuum  obtained  by  ignited  hydrocarbon  fluids. 

1859. 

784.     T.  M.  Meekins Production  of  motive  power,  and  projectile  and  ex- 

plosive  force  (provisional  protection  refused). 
1227.     J.  Nasmyth.— Improved  apparatus  for  obtaining  and  applying  motive 

power. 

I  I  2 


484  The  Gas  Engine 


NO. 


1345.     P.  Gambardella. — Obtaining  motive  power  from  mixture  of  hydrogen 

and  oxygen,  exploded  by  electric  spark. 
2767.     J.  Anderson — Coal  is  partially  burned  and  wholly  distilled  in  a  furnace 

into  which  the  proper  quantity  of  air  is  introduced. 

i860. 

335.     J.  H.  Johnson. — Improvements  in  obtaining  motive  power. 
615.      Pierre  Hugon.— Gas  and  air  exploded  in  bent  tube  over  water. 
878.     Michael  Henry — An  explosive  mixture  ignited  by  the  electric  spark. 
1585.     H.  F.  Cohade. — A  mixture  of  air  and  gas  is  exploded  in  a  chamber 

furnished  with  a  valve  to  produce  pressure. 

2743.     W.  E.  Newton.  — Heating  apparatus  consists  of  a  burner  from  which 
hydrogen  under  pressure  escapes  and  is  ignited  by  an  electric  spark. 
2902.     Pierre  Hugon. — Improved  method  for  igniting  explosive  gaseous  com- 
pounds. 

1861. 

107.  J.  H.  Johnson. — Improvements  upon  the  reciprocating  gas  motive 
power  engine,  No.  335/1860. 

1 66.  Jean  B.  Pascal. — Application  of  inflammable  gas,  produced  by  decom- 
position of  steam,  to  explosion  engine. 

3270.  W.  E.  Newton — Force  generated  by  the  explosion  of  a  mixture  of 
atmospheric  air  and  hydrogen. 

1862. 

2143.  C.  W.  Siemens  (provisional  only).  — Mixed  air  and  gas  are  admitted 
into  the  working  cylinder  and  ignited  by  electricity. 

3108.  Jacques  Arbos.— A  gas  engine  with  apparatus  for  generating  gas, 
forming  one  apparatus. 

1863. 

653.  Pierre  Hugon.— Explosive  force  of  the  gaseous  mixture  acts  upon  an 
intermediate  column  of  water,  and  thus  indirectly  upon  the  piston. 

1449.  W.  Clark.— Effecting  the  combination  of  oxygen  with  the  fuel,  and 
their  intermixture  with  the  burning  products  of  combustion,  causing 
motive  power. 

2098.     R.  A.  Brooman — Improvements  in  air  and  gas  engines. 

1864. 
1099.     M.  P.  W.  Boulton — In  connection  with  the  mode  of  working  steam 

and  caloric  engines  to  employ  that  portion  of  heat  which  is  generated 

by  combustion  of  the  fuel. 
1173.     F.  H.  Wenham — Engines  worked  by  explosive  mixtures. 


Appendix  II  485 


NO. 


1288.     J.  E.  Holmes  (provisional  only) — Vacuum  by  explosion. 

1291.  M.  P.  W.  Boulton. — Improvements  in  engines  worked  by  heated  air 
or  gases  mixed  with  steam. 

1599.     B.  F.  Stevens — Applying  petroleum  vapour  mixed  with  air. 

1636.  M.  P.  W.  Boulton. — Improvements  in  obtaining  motive  power  from 
aeriform  fluids. 

3044.  M.  P.  W.  Boulton. — Improvements  in  heating  aeriform  fluids  by  in- 
jecting some  substance  in  a  state  of  fusion  (chlorides,  &c.). 

1865. 

501.     M.  P.  W.  Boulton. — Improvements  in  obtaining  motive  power  from 

aeriform  fluids  and  from  liquids. 
827.     M.  P.  W.  Boulton — Obtaining  motive  power  from  aeriform  fluids  and 

liquids. 

905.     John  Pinchbeck  (provisional  only) — The  connection  of  the  exhaust 
pipe  of  the  cylinder  with  a  condensing  chamber  of  engines  worked 
.  by  explosion  of  air  and  gas. 

986.     Pierre    Hugon. — Effecting  the  combustion  or   explosion  of  gases  by 
means  of  slide  valves  carrying  gas  burners  supplied  with  gas  under 
pressure. 
1915.     M.  P.  W.  Boulton — Improvements  in  obtaining  motive  power  when 

heated  air  or  aeriform  fluid  is  employed. 

1992.     M.  P.  W.  Boulton. — Method  for  utilising  a  larger  portion  of  heat. 
2600.     W.  E.  Gedge.— Expansion  engine. 

1866. 

27.  T.  T.  Macneil  (provisional  only). — Motive  power  is  produced  by  means 
of  a  receptacle  containing  incandescent  fuel  into  which  is  forced 
the  requisite  air  for  combustion. 

181.     W.  Clark  (provisional  only).— Motive  power,  heated  gas  or  air. 
434.     C.  D.  Abel. — The  explosion  of  a  mixture  of  air  and  gas  drives  up  a 

light  piston. 

434.     C.  D.  Abel.  —Gas  engine  in  which  the  explosion  of  air  and  gas,  ignited 
by  a  gas  jet  or  electric  spark,  drives  up  a  piston. 

434.     C.  D.  Abel Regulating  power  of  explosion. 

738.     M.  P.  W.  Boulton.— Generating  and  applying  heat  for  the  production 

of  motive  power  and  steam. 
3125.     R.  George.  — Improvements  where  motive  power  is  obtained  by  action 

on  a  piston  traversing  to  and  fro  within  a  vibrating  cylinder. 
3363.     J.  Anderson.— Improvement  on    No.    2767/1859,    the   connection  of 

the  piston  with  shield  shell. 

3448.     W.  Clark.— Improvements  in  manufacture  of  hydrogen  gas  and  its 
applications  for  lighting  and  heating,  and  as  a  motive  power. 


486  The  Gas  Engine 

1867. 


NO. 


422.     R.  Shaw  (provisional  only). — Explosion  engine  details. 
499.      Kinder  &  Kinsey.— Improvements  in  gas  engines. 
571.     A.  V.  Newton. — Improvements  in  gas  engines. 

633.  A.  L.  Normandy. — Improvements  in  engines  worked  by  heated  air  or 
gases. 

1392.  William  Smyth.  — Motive  power  for  actuating  apparatus  for  navigating 

the  air. 

1575.  H.  A.  Bonneville. — Obtaining  motive  power  by  means  of  an  over- 
heated mixture  of  air  and  steam. 

2245.  C.  D.  Abel. — Combined  gas  and  air  engine.  The  explosion  of  a  mix- 
ture of  gas  and  air  propels  a  light  piston. 

3237.  W.  E.  Gedge  (provisional  only). — The  burnt  gases  are  condensed  after 
their  action  upon  the  driving  piston  in  order  to  produce  a  vacuum. 

3690.     W.  E.  Newton.  —Motors  for  generating  motive  power. 

1868. 
354.     A.  M.  Clark. — Manufacture  of  gases  for  a  gas  engine. 

1393.  G.  B.  Babacci A  vertical  gas  engine. 

1878.  J.  Bourne. — Production  and  application  of  motive  power.  Air  and 
fuel,  either  solid,  powdered,  liquid,  or  gaseous,  are  blown,  after  being 
made  hot,  into  a  hot  chamber,  a  pump  or  steam  jet  being  used. 

1988.  M.  P.  W.  Boulton. — Apparatus  for  obtaining  motive  power  by  the 
combustion  of  aeriform  inflammable  fluid. 

2264.  J.  Gill. — Improvements  in  the  construction  of  engines  for  motive 
power. 

2680.  J.  M.  Hunter. —A  vessel  is  provided  with  motive  power  for  aerial  pro- 
pulsion— explosion  of  mixture. 

2808.  Bower  &  Hollinshead. — The  construction  of  engines  in  which  the 
motive  power  is  derived  from  the  force  of  the  explosion  of  air  and 
gas. 

3146.  J.  Robertson. —The  generation  of  steam  or  gases  to  actuate  motive 
power  engines. 

3264.  E.  A.  Rippingille.— Motive  power  obtained  by  mixing  the  products 
of  combustion  with  steam. 

3594-  Jonn  Bourne. — Production  of  heat,  and  generation  and  application  of 
motive  power. 

1869. 

1375.     Franklin  &  Dubois  (provisional  only). — Gas  engine. 
1435.     H.  Bessemer. — Blast   furnaces   and   blast  engines,  and   utilising  the 

gaseous  products  from  blast  furnaces. 
1748.     A.   M.   Clark    (provisional   only) — Apparatus   for  producing   motive 

power  by  the  use  of  steam  or  compressed  gases. 


Appendix  II  487 

Hydes  &  Bennett.— Propelling  ships  by  means  of  heated  compressed 

air  and  products  of  combustion  combined. 
3178.     A.  H.  Brandon. — Gas  or  vapour  engine. 
3585.     W.    Hetherington.— Improvements   in    the    arrangement    and    con-. 

struction  of  motive  power  engines  which  are  actuated  by  heated  air 

or  gases. 
3705.     J.  Bourne. — Production  of  heat  and  motive  power,  the  combustion  of 

solid,  liquid,  or  gaseous  fuel. 

1870. 

194.     J.  M.  Plessner. — Treatment  of  hydrocarbons  and  air  to  produce  motive 

power. 
440.      A.    H.    de   Villeneuve. — Machinery  for   generating,    obtaining,    and 

applying  motive  power. 
1352.     E.  P.  H.  Vaughan  (provisional  only).— Construction  of  gas  engines  in 

which  a  mixture  of  air  and  combustible  gas  is  introduced  into  a 

cylinder  between  two  pistons. 
1859.     John  Bourne. — Motive  power  is  produced  from  heat  derived  from  the 

combustion  of  solid,  liquid,  or  gaseous  fuel,  and  from  coal  reduced 

to  powder. 
2554.     William  Firth  (provisional  only). — Improvements  in  steam,  air,  and 

gas  engines. 
2959.     E.  P.   H.  Vaughan. — Gas  engine,   in  which  the  mixture  of  air  and 

combustible  gas  is  introduced  into  the  cylinder  between  two  pistons. 

1871. 

1724.     E.  N.  Schmitz.—  An  improved  gas  engine. 

2254.  G.  Haseltine. —Motive  power  produced  by  the  explosive  force  of 
gas. 

2326.  J.  Anderson.— Producing  current  and  developing  motive  power  mainly 
by  igniting  a  mixture  of  combustible  gas  and  air  in  a  chamber  or 
channel,  near  an  orifice,  through  which  the  gases  of  greatly  increased 
volume,  due  to  the  combustion,  issue  in  the  form  of  a  jet. 

2587.     J.  M.  Plessner. Obtaining  motive  power  from  the  explosion  of  gases. 

1872. 

387.     W.  R.  Lake.— Engines  operated  by  gunpowder,  gun-cotton,  or  other 
explosive  material. 

821.     M.  A.  Soul Navigable  balloon  worked  by  a  gas  engine. 

1126.  T.  N.  Palmer  (provisional  only).— An  explosive  gas  engine.  Any 
fluid  carburetted  hydrogen  gas  or  fluid,  in  the  form  of  spray,  is 
introduced  into  a  cylinder,  where  by  the  access  of  atmospheric  air 
its  combustion  produces  motive  power. 


488  The  Gas  Engine 


NO. 


1423.  P.  Jensen.— The  construction  of  coke  ovens  and  utilisation  of  the 
waste  heat  therefrom  for  generating  gas  for  gas  engines  and  other 
purposes. 

1594.     W.  E.  Newton. — Explosion  engine. 

2293.  J.  Young. — Motive  power  obtained  from  vapours  given  off  by  the 
volatile  hydrocarbons  obtained  from  petroleum  and  paraffin  oils. 

3228.  W.  R.  Lake. — The  warming  of  air  (for  heated  air  motor)  effected  by 
means  of  tar,  or  other  cheap  liquid  fuel,  placed  in  a  closed  cylinder 
and  ignited. 

3481.  E.  T.  Hughes  (provisional  only). — The  use  of  any  liquid  hydrocarbon, 
such  as  naphtha  or  petroleum,  which  in  a  divided  state,  mixed  with 
atmospheric  air,  is  injected  behind  a  piston  in  a  cylinder,  and  when 
ignited,  produces  power  by  the  explosion  or  combustion. 

3641.  G.  Haseltine.  —  Utilising  the  vapour  of  hydrocarbon  oils  or  the  pro- 
ducts thereof,  or  similar  substances,  for  obtaining  motive  power. 

1873- 

272.     W.  E.  Sudlow. — Rotary  engines  worked  by  hot  air,  gas,  explosive  or 

otherwise,  or  by  water  pressure  or  steam. 

329.  G.  Rydill. — Steam  boilers  and  furnaces,  heating  air  and  gases,  and 
producing  motive  power  from  a  mixture  of  steam  and  products 
of  combustion  for  working  a  steam  engine,  and  for  other  purposes. 

1628.  J.  Imray  (provisional  only).  —  Method  of  and  apparatus  for  obtaining 
motive  power  from  heated  air,  gas,  or  gaseous  products  of  combus- 
tion admitted  to  a  cylinder  at  the  pressure  of  the  atmosphere. 

1946.  J.  Imray. — Obtaining  motive  power  from  heated  air,  gas,  or  gaseous 
products  of  combustion  admitted  to  a  cylinder  at  the  pressure  of  the 
atmosphere  and  cooled  therein,  so  that  their  pressure  on  one  side 
of  the  piston  being  reduced  below  that  of  the  atmosphere,  the  ex- 
cess of  atmospheric  pressure  on  the  other  side  of  the  piston  shall 
effect  its  propulsion. 

3848.  W.  R.  Lake. — Gas  engines  driven  by  the  explosion  of  combustible 
gas  or  vapour  mixed  with  air. 

4088.  F.  W.  Turner. — Gas  engines,  in  which  a  wheel,  arranged  with  a  pro- 
jecting rim  having  bevelled  grooves  on  the  inside,  is  keyed  on  the 
main  shait. 

1874. 

25.  R.  Gottheil.  — An  explosive  gas  engine,  having  a  cylinder  open  at  one 
end,  and  provided  with  two  pistons,  one  of  which  may  be  termed 
the  working  piston,  and  is  connected  in  the  usual  way  to  a  crank  on 
the  main  shaft,  while  the  other,  which  may  be  called  the  loose  piston, 
has  a  rod  passing  through  the  cylinder  cover,  and  through  the  two 
friction  cheeks  mounted  on  levers,  so  as  to  admit  of  free  movement 


Appendix  II  489 

NO. 

of  the  piston  rod  in  one  direction,  while  its  movement  in  the  other 
direction  is  checked,  owing  to  the  cheeks  embracing  the  rod  tightly. 
414.  C.  D.  Abel. — Gas  engine,  in  which  a  slide  is  arranged  to  operate  upon 
a  single  passage  for  inlet  to  and  outlet  from  the  cylinder  ;  this 
engine  is  regulated  by  a  governor,  so  as  to  economise  the  expendi- 
ture of  gas. 

486.     S.  Ford. — A  rotary  gas  engine  worked  by  the  explosive  force  of  gas. 
493.     J.  Hock.  — Engines  worked  by  the  combustion  of  petroleum,  naphtha, 
or  other  liquid  hydrocarbons,  such  combustion   producing  pressure 
in  a  cylinder  to  work  a  piston  connected  to  a  crank  on  a  fly-wheel 
shaft. 

509.     R.  M.  Marchant. — Combined  air,  steam  and  caloric  engine. 
605.     C.  D.  Abel. — Improvements  in  gas  motor  engines. 
777.     J.  D.  Ridley. — Aerial  machine,  in  which  a  piston  actuates  the  wings  of 
the  apparatus,   causing   it   to  reciprocate  in  a  cylinder  by  alternate 
explosions  of  gunpowder,    or  other  explosive  agent,  fired  by  elec- 
tricity. 

961.  C.  Carobbi  &  G.  Bellini.— Locomotive  and  other  engines,  worked 
by  air  compressed  by  the  combustion  of  fulminating  matters,  such 
as  cotton,  hemp,  linen,  tow,  or  similar  substances,  formed  into  a 
rope,  and  treated  with  a  mixture  of  concentrated  azotic  and  sul- 
phuric acid. 
1652.  E.  Butterworth  (provisional  only).— Preventing  the  over-heating  of  a 

cylinder,  exhaust  valve,  and  adjacent  pipes. 
2209.  G.  Haseltine.— Improvements  in  gas  engines. 
2441.  F.  Jenkin.— -Thermo-dynamic  engine,  or  '  fuel  engine,' the  primitive 

type  of  which  is  Stirling's  air  engine. 
2795.     J-  H-  Johnson.  — Generating  and  applying  the  motive  power  of  gases. 

3189.  R.  M.  Marchant  (provisional  only). —Combined  air,  steam,  and  caloric 

engines.     Gas  used  as  fuel. 

3190.  R.  M.  Marchant  (provisional  only).— Steam  and  other  motive  power 

engines,  and  manufacture  of  gas. 

3205.     F.  W.  Crcssley. — Improvements  in  gas  motor  engines. 
3257.     C.   T.   E.   Lascelles.  — Gas  engines  for  propelling  tramway  cars   and 

other  vehicles. 
4410.     Kirkwood,  Lascelles,   &  Hall  (provisional  only).— Gas  engines  used 

as  motors  for  tramway  cars  and  other  vehicles. 

I875. 
71.     C.  D.  Abel.— Motor  engines  worked  by  gas  or  combustible  vapour  and 

air. 

175.     P.  Vera.— Gas  and  hot  air  engines. 
265.     E.  C.  Mills  and  H.  Haley.  -  Explosive  gas  engines. 
744,     J.  F.  Dickson.— Improvements  in  air  and  gas  engines. 


49O  The  Gas  Engine 


NO. 


2016.     De  V:   Bruce  &    T.    M.  Antisell.— Utilising  the  expansive  force   of 

vapours   or    gases,    either    by   gradual   pressure   or   explosion,    in 

engines. 
2334.     W.  \V.  Smyth  &  G.  G.    Hunt. — Gas  engine  with  two  single-acting 

cylinders. 

2826.     R.  Hallewell.— Explosive  gas  engines. 

3221.     F.  W.  &  W.  J.  Crossley. — Improvements  in  gas  motor  engine. 
3274.     Q.  L.  Brin.  —  Obtaining  motive  power  by  the  explosion  of  gas  and  air 

acting  directly  or  indirectly  on  water  or  oil. 
3615.     C.  D.  Abel. — Improvements  in  gas  and  air  engines. 
4326.     J.  H.  T.  Ellerbeck  &  J.  M.  Syers. — Explosive  gas  motor  (provisional 

only). 
4342.     E.  P.  Alexander.—  Gas  motive  power  engines,  and  means  of  regulating 

and  transmitting  their  motion  for  driving,  sewing,  electric,  and  other 

machines,  and  fans  or  pumps. 

1876. 

88.     Thacker  (provisional  only). — Improvements  in  gas  engines. 
132.     Crossley. — Improvements  in  gas  motor  engines. 
1034.     Kidd    (provisional   only). — Improvements   in   gas-producing  furnaces 

and  in  the  methods  of  utilising  the  gases  generated  therefrom. 
1520.     Wirth  (Humboldt  Manufacturing  Co.). — Improvements  in  gas  engines. 
1961.     Lascelles. — Improvements  in  gas  and  other  explosive  motive  power 

engines. 

2081.     Abel  (Otto). — Improvements  in  gas  motor  engines. 
2288.     Boulton. — Improvements   in   apparatus    whereby   combustion    under 

pressure  is  applied  to  generate  fluid  for  working  engines. 
2824.     Lin  ford. — Improvements  in   gas  engines  and  in  appliances  connected 

thereto. 
3191.     De  Kierzkowski. — Improvements  in  pressure   generators  for   motive 

engines,  and  in  the  application  of  motive  engines  to  the  propulsion  of 

tram  cars,  &c. 
3370.     Redfern  (Sack  &  Reunert).— Improvements  in  gas  motor  engines  and 

in  apparatus  connected  therewith. 
3435.     Simon    (provisional   only).— Improvements    in    the   construction    of 

engines   to   be  worked   by  power  derived  from   air  and  oil   com- 
bined. 
3444.     Johnson    (Wertheim).— Improvements    in    obtaining    and    applying 

motive  power,  and  in  the  apparatus  employed  therein. 
3620.     Boulton.  — Improvements  in  engines  worked  by  the  combustion  and 

expansive  force  of  an  inflammable  fluid  mixture. 
3767.     Boulton.— Improvements  in  apparatus  for  the  production  of  motive 

power  jointly  by  the  elastic  force  of  products  of  combustion,  and  of 

steam  or  vapour. 


Appendix  II  491 

NO. 

4987.  I lallewell.— Improvements  in  gas  motor  engines. 

4988.  Hallewell.—  Improvements  in  gas  and  water  motor  engines. 

1877. 

252.     Clerk.  — Improvements  in  motive  power  engines  working  with  hydro- 
carbon gas  or  vapour. 

491.     Otto  &  Crossley.  — Improvements  in  gas  motor  engines. 
711.     Roberts  (provisional   only).— Improved   machinery  or  apparatus  for 

propelling  tramway  cars  and  other  like  vehicles. 
766.     Boulton.  —Improvements  in  engines  worked  by  products  of  combustion 

either  alone  or  in  conjunction  with  other  elastic  fluid. 
819.     Hallewell. — Improvements  in  gas  motor  engines  and  in  the  valve  of 

such  engines. 

1063.     Lake  (Wertheim). — Improvements  in  gas  motor  engines. 
1470.      Linford. — Improvements  connected  with  gas  engines. 
2177.     Crossley  (F.  W.  &  W.  J.).  — Improvements  in  gas  motor  engines. 
2334.      Robson. — Improvements  in  engines  operated  by  the  combustion  of  gas 

or  vapour. 

2621.      Simon  &  Miiller  (provisional  only). — Improvements  in  gas  engines. 
2749.     Simon. — Improvements  connected  with  atmospheric  gas  engines. 
3024.     Mills  &  Haley.  —  Improvements  in  motive  power  engines  worked  by 
the  explosion  of  gas. 

3121.  Wilson  and  others  (provisional  only).  — Improvements  in  engines,  and 

apparatus  for  the  propulsion  of  vehicles  on  roads  and  rails. 

3122.  Wilson  and  others  (provisional  only).  —  Improvements  in  gas  motors. 
3159.     Johnson  (La  Societe   des   Moteurs  Lambrigot). — Improvements    in 

effecting  the  conversion  of  hydrocarbons,    &c.,    into   gas,  and  in 

apparatus  or  means  employed  therein,  and  in  or  for  the  production 

and  application  of  gaseous  mixtures. 
4052.     Weyhe.— Improvements  in  gas  motor  engines. 
4937.     Simon  (Kindermann)  (provisional  only). —Improvements  in  gas  motor 

engines. 

1878. 

10.     Hilton  &  J.  &  S.  Johnson  (provisional  only) — Improvements  in  the  ap- 
plication of  gas  motors  to  tram  cars  and  other  self-propelling  vehicles. 
228.     Ramsbottom.  —  Improvements  in  engines  for  obtaining  motive  power 

from  liquid  and  gaseous  fluids,  and  for  pumping  and  compressing. 
290.     Pieper  (Schaeffer)  (provisional  only). — An  improved  gas  motor. 
433.     Simon  (L.  &  R.).— Improvements  in  and  connected  with  gas  engines. 
942.     Linford. — Improvements  in  gas  engines. 
1 170.     Baron. — Improvements  in  motive  power  engines. 
1770.     Abel    (Otto)    (provisional   only).— Improvements    in    apparatus    for 
igniting  the  charges  of  gas  motor  engines. 


492  The  Gas  Engine 


NO. 


1798.  Halle  well.— Improvements  in  gas  engines,  applicable  in  part  to 
other  uses. 

1997.  Hannoversche  Maschinenbau-Actien-Gesellschaft,  The. — Improve- 
ments in  gas  engines  with  two  pistons. 

2037.  Clayton. — Improvements  in  gas  motor  engines  and  in  apparatus  con- 
nected therewith. 

2278.     Boulton  (provisional  only) — Improvements  in  gas  motor  engines. 

2474.  Johnson  (Frangois). — Improvements  in  obtaining  motive  power  and 
in  the  machinery  or  apparatus  employed  therein. 

2525.     Boulton  (provisional  only). — Improvements  in  gas  motor  engines. 

2609.     Boulton  (provisional  only). — Improvements  in  gas  motor  engines. 

2707.     Boulton. — Improvements  in  combined  gas  and  steam  motor  engines. 

2901.  Waller. — Improvements  in  gas,  steam,  air,  and  other  motive  power 
engines  and  in  apparatus  in  connection  therewith. 

3045.     Clerk.  —  Improvements  in  gas  motor  engines. 

3056.  Leichsenring. — Improvements  in  and  relating  to  engines  worked  by  gas 
or  other  fluid,  partly  applicable  to  apparatus  for  compressing  fluids. 

3444.     Cropper  &  Johnson. — Improvements  in  valves  for  gas  engines. 

3774.  Casson  (provisional  only). —Improved  means  and  apparatus  for  work- 
ing clocks  and  bells  (by  combustion  of  gas). 

3972.     Weatherhogg. — Improvements  in  gas  motor  engines. 

4630.     Foulis  (provisional  only). — Improvements  in  motive  power  engines. 

4760.  Duncan  &  W.  G.  Wilson  (provisional  only).— Improvements  in  gas 
motors. 

4782.  Lake  (Lay)  (provisional  only).  —  Improvements  in  apparatus  for  pro- 
pelling, guiding,  &c.,  torpedo  boats. 

4843.  Foulis. — Improvements  in  gas  and  hydrocarbon  engines,  and  in  ignit- 
ing the  gas  or  hydrocarbon,  applicable  for  other  purposes. 

4979.  Simon  and  another. —  Improvements  in  and  connected  with  gas  or 
hydrocarbon  engines. 

4987.  Lake  (Lay).— Improvements  in  apparatus  for  propelling,  guiding  &c. 
torpedo  boats. 

5092.     Halle  well.  —Improvements  in  gas  motor  engines. 

5113.     Crossley  and  another. — Improvements  in  gas  motor  engines. 


I879. 

2.  Williams  &  Baron.— Improvements  in  and  relating  to  atmospheric 
air  and  gas  motor  engines. 

309.  Pieper  (Krauss).—  A  gas  power  locomotive  for  tramways  and  for  rail- 
ways of  secondary  order. 

392.     Shaw  (provisional  only).— Improvements  in  gas  motor  engines. 

495.     Boulton.— Improvements  in  caloric  engines. 


Appendix  II  493 


NO. 


540.     Donald  (provisional  only).— Improvements  in  and  connected  with  gas 

engines. 
750.     Simon   (Todt)  (provisional   only).— Improvements   in  vapour  or  gas 

motor  engines. 
1161.     Graddon.— Improvements  in  machinery  or  apparatus  for  generating 

motive  power  &c.  &c. 

1270.     Turner. — Improvements  in  and  relating  to  gas  motor  engines. 
1450.     Halle  well. —  Improvements  in  compound  gas  engines. 
1500.      Linford. — Improvements  in  gas  engines. 
1727.     Purssell  (provisional  only).— Improvements  in  gas  engines  to  adapt 

them  for  locomotive  purposes. 
1912.      Holt  &  Crossley  (provisional  only).  — Improvements  in  machinery  for 

starting,  propelling,  and  stopping  vehicles,  and  in  the  apparatus  and 

appliances  connected  therewith,  more  particularly  with  reference  to 

gas  engines  &c.  &c. 

1933.     Sombart  (Buss). — Improvements  in  gas  engines. 
1947.     Newton   &    Cowper    (provisional    only). — Improvements    in    prime 

movers  and  apparatus  actuated  by  fluid  pressure,  applicable  wholly 

or  in  part  to  pumps  and  other  apparatus. 
1996.     Clark  (Fell).— Improvements  in  the  production  of  motive  power  and 

in  apparatus  for  the  same. 
2073.     Foulis.  — Improvements  in  that  class  of  motive  power  engines  known 

as  gas  or  hydrocarbon  engines. 

2152.     Woolfe. — Improvements  in  the  construction  of  gas  motor  engines. 
2191.     Benson  (Rider). — Improvements  in  gas  engines. 
2193.      Hurd. — A  condensing  or  non-condensing  compound  single  or  double 

acting  motive  power  engine,  worked  by  explosive  gases,  collected 

from  mines  or  otherwise,  in  combination  with  or  without  gun-cotton, 

or  with  gun-cotton  alone,  &c. 

2424.     Clerk.— Improvements  in  gas  motor  engines. 
2618.     Butcher  (provisional  only).— Improvements  in  gas  motor  engines. 
2732.     Johnson. — Improvements  in  gas  engines. 

3140.     Clayton.— Improvements   in   motor   engines  worked  by  gas  or  com- 
bustible vapour  and  air. 
3213.     Atkinson.— Improvements  in  gas  and  similar  engines  and  mechanism 

connected  therewith,  partly  applicable  to  other  purposes. 
3233.     Simon Improvements  in  gas  engines  worked  by  the  combustion  or 

explosion  of  a  compressed  mixture  of  gas  and  air  or  hydrocarbon 

and  air. 

3245.     Abel  (Daimler) Improvements  in  gas  motor  engines. 

3467.     Dalton  &  Kenworthy.— Improvements  in  propelling  carriages  and  in 

the  apparatus  employed  therein. 

3561.     Picking  &  Hopkins — Improvements  in  gas  motor  engines. 
3732.     Glaser  (Wittig  &  Hees) Improvements  in  gas  and  petroleum  engines. 


494  Th*  Gas  Engine 


NO. 


3905.     Alexander  (Angele) — Improvements  in  gas  motors. 

4101.     Emmet  &  Cousins. — Improvements  in  gas  engines. 

4337.     King. Improvements  in  and  connected  with  engines  actuated  by  the 

explosion  or  combustion  of  a  mixture  of  gas  and  air. 
4340.     Williams. Improvements  in  and  relating  to  atmospheric  air  and  gas 

motor  engines. 

4377-     Butcher Improvements  in  gas  motor  engines. 

4396.      Purssell An    improved    arrangement  of  apparatus  for  moving  tram 

cars  &c.  by  gas  engine  power. 
4483.     Graddon    (provisional    only) — An     improved    motive   power   engine 

actuated  by  an  explosive  fluid  or  gas,  part  of  which  may  be  applied 

to  other  gas  engines. 
4485.     Wigham  (provisional  only) — Improvements  in  gas  motor  engines. 

4492.     Shaw Improvements  in  gas  motor  engines. 

4499.     Holt  &  Crossley — Improvements  in  machinery  &c.   for  stopping  &c. 

the  direction  of  motion  of  vehicles  on  rails,  &c.,  more  particularly 

applicable  to  gas  engines,  but  also  suitable  for  other  motor  engines. 

4501.      Robson Improvements  in  gas  engines. 

4755..     Foulis Improvements  in  gas  engines. 

4820.     Edmonds  (Fra^ois) — A  new  or  improved  gas  motor  or  engine  and 

new  arrangements  of  mechanism  employed  with  the  same. 
5052.     Mills  &  Haley Improvements  in  gas  motor  engines. 

1880. 

9.     Pottle. Improvements   in    governors   for   steam    engines   and    other 

motors. 

117.     Robinson Improvements  in  gas  motor  engines. 

530.     Linford. — Improvements  in  and  connected  with  gas  engines. 

343.     Abel  (Daimler) Improvements  in  gas  motor  engines. 

474.     Butcher — Improvements  in  tramway,  locomotive,  and  other  engines, 

and  in  apparatus  connected  therewith. 

533.  Thompson  (Geisenberger) — Improvements  in  and  appertaining  to  gas 
engines,  or  engines  actuated  by  the  explosion  or  combustion  of  mixed 
gas  or  vapour  and  air. 

760.  Edwards — Improvements  in  motive  power  engines  actuated  by  the 
combustion  of  a  mixture  of  gas  and  air,  or  by  the  pressure  of  steam 
or  other  elastic  fluid,  parts  of  which  invention  are  also  applicable  to 
other  purposes. 

1131.     Johnson. —  Improvements  in  gas  engines. 
1653.     Beechey  (provisional    only).— Improvements    in    engines  worked  by 

gas  and  air  or  other  hydrocarbons. 

1692.     Williams  &  Malam.—  Improvements  in  and  relating  to  atmospheric  air 
and  gas  motor  engines. 


Appendix  II  495 


NO. 


1736.     Sombart. — Improvements  in  gas  engines. 

1969.     Haigh  &  Nuttall.— Improvements  in  gas  engines. 

2181.  Wordsworth. — Improvements  in  gas  motor  engines. 

2182.  Lake  (Lay).— Improvements  in  apparatus  for  facilitating  the  control 

and  operation  of  torpedo  boats. 

2290.     Hardaker.  — Improvements  in  road  vehicles  or  velocipedes. 
2299.     Livesey  (Livesey). — Improvements  in  gas  motor  engines. 
2344.     Robinson. —  Improvements  in  gas  motor  engines. 
2422.     Foulis. — Improvements  in  gas  engines. 
3140.     Lake  (Breittmayer). — Improvements  in  gas  engines. 
3176.     Northcott.  —  Improvements  in  engines  and  apparatus  for    producing 

motive  power  (relating  to  gaseous  fuel  engines). 
3182.     Turner. — Improvement  in  gas  motor  engines. 
341 1.     Holt  &  Crossley.— Improvement  in  locomotives  for  tramways  and  light 

railways. 

3512.     Aylesbury. —Improvements  in  gas  engines  or  motors. 
3607.     Jenner. — Improvements  in  gas  engines. 
3652.     Wilson. — Improvements  in  vertical   steam  and  other  motive  power 

engines. 
3685.     Williams  &  Malam. — Improvements  in  and  relating   to   atmospheric 

air  and  gas  motor  engines. 
3869.     Purssell.  —  Improvements  in  the  construction,  arrangement,  and  method 

of  action  of  gas  engines. 
3913.     Lawson  (provisional  only). — Improvements  in  velocipedes  and  in  the 

application  of  motive  power  thereto,  applicable  to  other,  &c. 
4050.     Robson. — Improvements  in  obtaining  and  applying  motive  power. 
4075.     Clayton.— Improvements  in  motor  engines  worked  by  gas  or  combus- 
tible vapour  and  air. 
4159.     Kesseler  (Henniges)  (provisional  only).— Improvements  in  the  Simon's 

steam  gas  motor  with  burning  flame  in  the  cylinder. 
4260.     Robinson. — Improvements  in  gas  motor  engines. 
4270.     Beechey. — Improvements  in  gas  motor  engines. 
4297.     Crossley. — Improvements  in  gas  motor  engines.       ^ 
4398.      Rhodes  and  others.— Improvements  in  gas  motor  engines. 
4419.     Benson  (Rider).  — Improvements  in  gas  engines. 
4547.     MacFarlane  (provisional  only). — A  new  or  improved  gas  engine. 
4633.     Bickerton  (provisional  only).— Improvements  in  gas  motor  engines. 
4819.     Muller.  —  Improvements  in  or  additions  to  gas  engines. 
4881.     Simon  &  Wertenbruch.  — Improvements  in  gas  motor  engines. 
5024.     Home  (provisional  only). — Improvements  in  gas  engines. 
5090.     Foulis  (provisional  only).-  Improvements  in  gas  engines. 
5101.     Richardson  (provisional  only). —Improvements  in  gas  engines  and  in 

apparatus  connected  therewith  for  the  supply  of  gas  to  them. 
5130.     Livesey  (Livesey).  — Improvements  in  compound  gas  motor  engines. 


496  The  Gas  Engine 

NO. 

5219.     Fiddes. — Improvements  in  gas  motor  engines. 

5269.     Wigham  (provisional  only). — Improvements  in  locomotive  engines  for 

tramways,  &c. 
5347.     Robinson. — Improvements  in  engines  to  be  worked  by  steam,  air,  or 

gas. 

5471.     Hutchinson. — Improvements  in  gas  motor  engines. 
5479.     Graddon. — Improvements  in  machinery  or  apparatus  for  obtaining  and 

applying  motive  power,  partly  applicable  to  other  purposes. 

1881. 

60.  Abel  (Otto). — Improvements  in  gas  motor  engines. 

180  Foulis. — Improvements  in  gas  engines. 

320.  Sombart—  Improvements  in  gas  engines. 

370.  Holt   &   Crossley. — Improvements    in    connection    with    gas   motor 

engines,  and  locomotives  worked  thereby. 

532.  Fielding. — Improvements  in  gas  motor  engines. 

565.  Allcock. — Improvements  in  gas  engines. 

798.  Ord  (provisional  only).  —  Improvements  in  gas  engines. 

799.  Graddon. — An  improved  construction  of  gas  engines. 

811.     Haigh  &  Nuttall. — Improvements  in  the  construction  of  gas  engines. 
867.     Wenham.  — Improvements  in  combined  gas  and  heated  air  engines. 
1074.     Bauer  &  Lamart.  —  Improvements  in  gas  engines. 
1089.     Clerk. — Improvements    in    motors    worked    by   combustible  gas    or 

vapour. 
1 202.     Boulton.  — Improvements   in    caloric    engines,    wherein   the   working 

fluid  is  heated  by  internal  combustion  of  gas. 
1363.     Bickerton. — Improvements  in  gas  motor  engines. 
1382.     Groth  (Schoufeldt  and  another). — A  new  or  improved  reversible  rotary 

engine. 

1388.  Ewins  &  Newman. — Certain  improvements  in  gas  engines. 

1389.  Boulton. — Improvements  in  caloric  engines  wherein  the  working  fluid 

is  heated  by  internal  combustion  of  gas. 

1409.     Gwynne  &'  Ellis. — Improvements  in  gas  motor  engines. 

1541.     Benier. — Improvements  in  gas  engines. 

1723.  Watson.— An  improved  method  of  exploding  gases  used  in  gas 
engines. 

1763.     Watson  (provisional  only). — Improvements  in  gas  engines. 

1765.  Edwards. — Improvements  in  motive  power  engines  actuated  by  the 
combustion  of  a  mixture  of  gas  and  air. 

2083.     Robson. — Improvements  in  motive  power  engines. 

2122.  Dougill.— Improvements  in  gas  motor  engines,  in  the  method  of  regu- 
lating the  speed  thereof,  and  of  admitting  combustible  material  into 
the  cylinder  and  allowing  the  escape  of  exhausted  products,  &c. 


Appendix  II  497 


NO. 


2227.  Crossley.— Improvements  in  the  method  and  apparatus  for  supplying 
gas  to  movable  gas  motor  engines. 

2280.     Ford. — Improvements  in  gas  engines. 

2504.     Siemens. — Improvements  in  gas  motors  and  producers. 

2564.  Wigham.—  Improvements  in  locomotive  engines  for  tramways,  rail- 
ways, &c. 

2645.     Pinkney. — Improvements  in  gas  engines. 

2765.     Levassor. — An  improved  motive  power  engine. 

2919.  Watson. — An  improved  means  or  method  of  exploding  gases  in  gas 
engines. 

2931.     De  Pass  (Kortung). — Improvements  in  gas  engines. 

2961.      Beechey.  —  Improvements  in  gas  motor  engines. 

2967.     Wastfield.  —  Improvements  in  gas  engines. 

2990.     Linford  &  Linford. — Improvements  in  and  connected  with  gas  engines. 

3113.  Eteve  &  Lallement. — A  new  or  improved  motive  power  engine 
operated  by  hydrocarburetted  air. 

3275.     Ord.— Improvements  in  gas  motor  engines. 

3330.  Brydges  (Schiltz).—  Improvements  in  gas,  hydrocarbon,  and  other 
motive  power  engines. 

3367.  Boulton. — Improvements  in  engines  wherein  a  piston  is  propelled  in  a 
cylinder  by  ignition  of  inflammable  gas  or  fluid. 

3415.  Justice  (Osam). — Improvements  in  the  utilisation  of  the  gaseous  pro- 
ducts of  combustion,  and  in  apparatus  therefor  (provisional  only). 

3450.  Crossley  &  Holt  (provisional  only). — An  improved  governor  for  gas 
motor  engines. 

3527.     Lucas. — Improvements  in  gas  engines. 

3536.  Stern,  Clerk,  &  Handyside.— Improvements  in  refrigerating  machines, 
and  in  part  applicable  to  gas  motors,  &c. 

3561.  Kirkhove  &  Snyers.— A  new  or  improved  method  and  machinery  for 
direct  propulsion  of  land,  water,  and  aerial  motors  or  engines,  appli- 
cable also  to  stationary  engines. 

3715.  Williams.  —Improvements  in  gas  engines  and  the  automatic  generation 
of  gas  therefor. 

3786.  Butcher. — Improvements  in  gas  motor  engines,  and  in  arrangements 
for  starting  and  re-starting  the  same. 

4086.     Atkinson.— Improvements  in  gas  engines. 

4137.  Watson.  -  Improvements  in  obtaining  motive  power  by  means  of  com- 
bustible gas  or  vapour,  and  in  apparatus  therefor. 

4223.      King.  —Improvements  in  gas  motor  engines. 

4244.  Abel  (Spiel).— Improvement  in  motor  engines  worked  by  combustible 
gases  or  vapours  and  steam. 

4288.  Simon  &  Wertenbruch.  —  Improvements  in  the  construction  and 
method  of  action  in  gas  engines. 

4340.     Wordsworth  and  others.— Improvements  in  gas  motor  engines. 

K  K 


498  The  Gas  Engine 

NO. 

4402.     Weatherho^g. — Improvements  in  single  and  double  acting  compound 

air  and  gas  motor  engines. 
4407.     Drake  &  Muirhead  (provisional  only). — Improvements  in  and  connected 

with  gas  engines. 

4589.     Benier  &  Lamart  (provisional  only). — Improven  ents  in  gas  engines. 
4608.     Watson. — Improvements  in  gas  engines. 
4830.     Lake  (Lay). — Improvements  in  and  relating  to  boats  to  be  propelled 

by  gas,  &c. 

5178.     Shaw. — Improvements  in  gas  motor  engines. 
5201.     Tonkin. — Improvements  in   motive   power   engines   actuated    by  the 

combustion  or  explosion  of  mixtures  of  gas  or  combustible  vapour 

with  air,  &c.  ;  applicable  to  other  purposes. 
5259.      Rhodes  (provisional  only). — Improvements  in  and  appertaining  to  gas 

engines  or  engines  actuated  by  the  explosion  or  combustion  of  mixed 

gas  or  vapour  and  air. 
5350.     Siemens. — Improvements  in   engines  worked  by  the  combustion   of 

gaseous  fuel. 
5456.     Williams. — Improvements  in  and  relating   to  atmospheric  air  and  gas 

motor  engines. 
5469.     Crossley  &  Holt. — Improvements  in  ga?  motor  engines,  part  of  which 

improvements  are  applicable  to  steam  engines,  &c. 
5483.     Griffin. — Improvements  in  gas  motor  engines. 
5534.     Beck  (Montelar).  —  A  gas  locomotor  for  the  locomotion  of  carriages,  &c. 

(provisional  only). 
5575-     Quick  and  another. — Improvements  in  tramway  locomotives  and  other 

locomotives  or  motive  power  engines. 

1882. 

362.  Turner.  —Improvements  in  gas  engines. 

397.  Emmet. — Improvements  in  gas  engines. 

417.  Withers. — Improvements  in  gas  engines. 

579.  Johnson  (Bis;chop). — Improvements  in  gas  engines. 

614.  Haigh  &  Nuttall. — Improvements  in  the  construction  of  gas  engines. 

659.  Wastfield  (provisional  only). —Improvements  in  gas  engines. 

678.  Watson  (provisional  only). —Improvements  in  gas  engines. 

703.  Wordsworth  &  Lindley.— Improvements  in  j.as  engines. 

994.  Fielding.  —Improvements  in  and  connected  with  gas  motor  engines. 

1026.  Niel. —Improvements  in  gas  engines. 

1318.  Beechey. — Improvements  in  gas  motor  engines. 

1360.  Sumner. — Improvements  in  gas  motor  engines. 

1590.  Skene.—  Improvements  in  gas  motor  engines. 

1717.  Drake   &    Muirhead.— Improvements    in    and    connected    with    gas 
engines. 


Appendix  II  499 

NO. 

1754.     Anderson  &  Crossley.— Improvements  in  the  ignition  apparatus  of  gas 

motor  engines. 

1868.      Dufrene,  Benier,  &  Lamart. — Improvements  in  gas  engines. 
1874.      Brown. — Improved  means  of,  and  apparatus  for,  the  production  of  gas 

by  the  combustion  of  carbon  compounds,  £c. 
1910.      Skinner  (provisional  only) — Improvements  in  engines  which  are  driven 

by  means  of  the  explosive  force  of  gases. 
2008.      Glaser  (Teichmann)  (provisional  only).  — Improvements  in  caloric  and 

gas  power  engines. 

2057.  Sombart. — Improvements  in  gas  engines. 

2058.  Porteous. — Improvements  in  gas  engines. 
2126.     Worssam. — Improvements  in  gas  motor  engines. 

2202.     Clayton.  —  Improvements  in  motor  engines  worked  by  gas  or  combus- 
tible vapour  and  air. 
2231.      Russ  (provisional  only). — Improvements  in  the  manufacture  of  gas  for 

lighting,  heating,  &c.,  and  for  utilising  the  same  for  motive  power. 
2257.      Nobbs.  —  Improvements  in  gas  engines. 
2329.      Hutchinson.  —  Improvements  in  gas  engines. 
2337.      Guthrie  (provisional  only).  —  Improvements  in  and   relating  to  engines 

and  apparatus  connected  therewith  for  developing  the  expansive  force 

of  air  or  gas  and  utilising  the  same  for  motive  power. 
2342.     Watson  (provisional  only).  —Improvements  in  gas  engines. 
2345.     Bickerton  and  another. — Improvements  in  and  applicable  togas  motor 

engines. 
2423.     Thompson    (Marcus). —  Improvements  in   or   appertaining  to  motors 

actuated  by  the  explosion  of  comminuted  liquids,  &c. 
2527.     Davey. — Improvements  in  apparatus  for  the  production  of  inflammable 

gas   and  applying   its   combustion   for   the   production   of   motive 

power. 

2751.     Braham  &  Seaton  (provisional  only). — Improvements  in  gas  engines. 
2753.  .  Wordsworth  &  Wolstenholme.— Improvements  in  gas  motor  engines. 
3435.     Abel  (Beissel).—  Improvements  in  gas  motor  engines. 
3449.     Holt   &   Crossley    (provisional   only) — Improvements  in   gas   motor 

engines. 
3787.     Davey.  — Improvements  in  apparatus  for  generating  elastic  fluid  under 

pressure  ;  available  for  working  engines. 
3819.     McGillivray.— Improvements  in  gas  engines. 
4364.     Clark  (Schweizer).—  Improvements  in  gas  engines. 
4378.     Atkinson. — Improvements  in  gas  engines. 
4388.     Atkinson.— Improvements  in  gas  engines. 
4418.     Watts  &  Smith.  — Improvements  in  and  connected  with  motors  worked 

by  combustible  gas,  vapour,  steam,  &c. 
4489.     Crossley.  —Improvements  in  gas  motor  engines. 
4755-     Wastfield.  —  Improvements  in  and  relating  to  gas  engines. 

K  K  2 


5oo  The  Gas  Engine 


Wastfield   (provisional  only). — Improvements  in  and  relating  to  gas 

engines. 

Baldwin  (provisional   only). — Improvements  in  gas    engines   and   in 
apparatus  connected  therewith. 

4948.  Clerk.— Improvements  in  motive  power  engines  worked  by  combus- 
tible gas  or  vapour. 

5042.      Gedge  (Marti  &  Quaglio). — Improvements  in  rotary  gas  engines. 

5188.     Ashbury  and  others. — Improvements  in  gas  motor  engines. 

5371.  Russ  (provisional  only). — Improved  arrangement  of  machinery  for  the 
manufacture  of  gas  for  lighting,  heating,  and  motive  power  pur- 
poses. 

5506.      Mewburn  (Goubet). — An  improved  rotary  gas  or  explosion  engine. 

5510.      Maynes.' — Improvements  in  gas  motor  engines. 

5527.  Dyson  (provisional  only). — Improvements  in  or  applicable  to  gas 
engines  employed  in  connection  with  tramcars,  &c. 

5782.      Watson. — Improvements  in  gas  engines. 

5819.     Whittaker. — Improvements  in  or  applicable  to  gas  motor  engines. 

5825.      Odling  (provisional  only). — Improvements  in  gas  motor  engines. 

6130.     Clark  (Laurent). —Improvements  in  gas  engines. 

6136.  Bennet  &  Walker. — Improvements  in  motive  power  engines,  which 
improvements  are  also  applicable  to  gas  engines. 

6214.     Watson. — Improvements  in  gas  engines. 

1883. 

19.     Forest. — An  improved  construction  of  gas  motor  engine. 
21.     Woodhead. — Improvements  in  gas  motor  engines. 
130.     Odling. — Improvements  in  gas  motor  engines. 
132.     Lake  (Maxim)  (provisional  only).  —Improvements  in  gas  engines. 
300.     Williams. — An  improvement  in  engines  for  motive  power,  compression, 

and  other  like  purposes. 

326.     Linford  &  Cooke. — Improvements  in  gas  engines. 
388.     Howard     &     Bousfield     (provisional    only).  —  Improvements    in   gas 

engines. 
499.     Weatherhogg.  —  Improvements  in  air  and  gas  motors  and  apparatus  for 

the  production  of  gas  therefor. 

638.     King  &  Cliff.— Improvements  in  gas  motor  engines. 
781.     Townsend  &  Davies.  — Improvements  in  gas  motor  engines. 
836.     Imray  (Schweizer) — An  improvement  in  gas  motor  engines. 
911.     Capell.  -  Improvements  in  motors  worked  by  air,  gas,  &c. ,  or  explosive 

mixtures,  &c. 

999.     Clark  (Kabath) — Improvements  in  gas  and  other  engines. 
1010.     Andrew — Improvements  in  gas  engines. 
1019.     Handford    (Edison).— Improvements   relating    to    the    operation    of 

electrical  generators  by  gas  engines. 


Appendix  II 


NO. 


1060.      Martini. — A  new  gas  motor. 

1098.     Wastfield.—  Improvements  in  and  applicable  to  gas  engines. 
1116.     Steel.  &  Whitehead. — Improvements  in  gas  engines. 
1501.     Marchant  &  Wrigley — Improvements  in  the  application  and  storage 
of  illuminating  or  other  like  gas  to  motors  for  driving  tramcars  or 
other  vehicles,  and  for  the  purpose   of  starting  and  working   gas 
engines,  and  in  means  employed. 

1677.     Abel  (Otto).— Improvements  in  gas  motor  engines. 
1722.     Crossley  (provisional  only) — An    improvement   in  gas  motor  engine 

slide  apparatus. 
1835.     Butcher. —Improvements  in  gas  motor  engines  and  in  applying  them 

to  pumping  purposes. 
2192.     Justice    (Hale).— Improvements  in  and  connected  with   gas   engine, 

and  in  the  method  and  means  for  regulating  explosive  charge. 
Picking  &  Hopkins.  — Improvements  in  gas  motor  engines. 
Haigh  &  Nuttall — Improvements  in  gas  engines. 
Nash — Improvements  in  the  means  for  operating  gas  engines. 
Pieper  (Korting  &  Lieckfeld).—  Improvements  in  gas  motors. 
Crowe  and  others. — Improvements  in  gas  caloric  motive  engines. 
Thompson  (Marcus) — Improvements  in  gas  motor  engines. 
Whitehead. — A  new  or  improved  gas  motor  engine. 
Russom  (provisional  only). — Improvements  in  gas  engines. 
Andrew — Improvements  in  gas  motor  engines. 

Williams. — Improved  means  of,  and  apparatus  for,  converting  recipro- 
catory  into  rotary  motion  in  gas  and  other  explosive  engines,  and  in 
hydraulic,  steam,  air,  or  other  fluid  motors  ;  also  for  effecting  and 
governing  explosions  in  gas  and  other  such  engines,  parts  of  which 
are  also  applicable  as  air  and  other  fluid  compressors. 
Fielding — Improvements  in  gas  motor  engines,  in  part  applicable  to 

other  engines. 

Crossley.— Improvements  in  gas  motor  engines. 
Dougill. — Improvements  in  gas  motor  engines. 
Niel — Improvements   in    the   construction   and   arrangement  of  gas 

engines. 

Kirchenpauer  &  Philippi. — Improvements  in  gas  motor  engines. 
Foulis — Improvements  in  gas  engines. 
Holder — Improvements  in  gas  motors. 

Lake  (Gardie).  —  Improvements  in  and  relating  to  gas  engines. 
Wordsworth  &  Lindley — Improvements  in  gas  motor  engines. 

Pickering Improvements  in  gas  engines. 

Button  (Spiel).  —Improvements  in  gas  or  inflammable  liquid  engines 

or  prime  movers. 

Quack  (provisional  only) — Improvements  in  gas  engines. 
Clerk Improvements  in  gas  motors. 


5O2  The  Gas  Engine 


NO. 

4080.     Griffin.  — Improvements  in  the  arrangement  and    construction  of  gas 

motor  engines. 
4193.      Racholz  (provisional  only) — Improvements  in  oil-gas  engines,  whereby 

the  said  engine  produces  its  own  gas  from  oil  waste. 
4242.      Ladd  (Serrell). — Improvements  in  and  relating  to  gas  engines. 
4260.     Clark  (Economic  Motor  Company). — Improvements  in  gas  engines. 
4291.     Andrew — Improvements  in  gas  engines. 

4455.     Haddan  (Schiltz) — Improvements  in  gas  and  petroleum  engines. 
4816.     Williamson  and  others. — Improvements  in  gas  motor  engines. 
5020.     Briscall  and  another  (provisional  only) — Improvements  in  and  relating 

to  gas  motor  engines. 
5042.     Lake  (Kabath) — Improvements  in  electrical  igniting  apparatus  for  gas 

engines. 

5085.     Bullock. — Improvements  in  gas  motor  engines. 
5113.     Bull — Improvements  in  gas  engines. 
5265.     Justice    (Hale) — Improvements  in  and  connected  with  gas  engines, 

and  in  the  means  and  method  of  supplying  explosive  charges  thereto. 
5297.     Wirth    (Sohnlein)    (provisional    only) Improvements   in    petroleum 

motors. 

53 1 5-     Johnson  (Lenoir) — Improvements  in  gas  engines. 
5331.      Robson  (provisional  only) — Improvements  in  gas  engines. 
5406.      Picking  &  Hopkins.  —Improvements  in  gas  motor  engines. 
5543.     Nash.  --Improvements  in  the  construction  of  gas  engires,  and  in  certain 

methods  of  operating  the  same. 
5570.     Williamson  and  others  (provisional  only). — Improvements  in  gas  motor 

engines. 

5632.     Nash. —Improvements  in  the  construction  of  gas  engines. 
S^SS-     Nash. — Improvements  in  the  construction  of  gas  engines. 
5721.     Mills. — Improvements  in  gas  motor  engines. 
^784.     Groth  (Daimler) — Improvements  in  gas  or  oil  motors. 
5923.     Sombart— Improvements  in  gas  engines. 
5^28.     Welch  &  Rapier — Improvements  in  gas  engines. 
5951.     Campbell  (provisional  only).  — Improvements  in  gas  motor  engine. 
5956.     Wastfield.— Improvements  in  and  relating  to  gas  engines. 
5976.     Tonkin. —Improvements   in   motive  power  engines   actuated    by  the 

combustion  or  explosion  of  mixtures  of  gas  or  combustible  vapours 

with  air,  parts  of  which  improvements  are  applicable  to  other  engines. 

1884. 

325  Hargreaves.— Increasing  efficiency  of  thermodynamic  engines. 

454-  Skene — Improvements  in  gas  engines. 

560.  Steel  &  Whitehead.  —  Improvements  in  gas  engines. 

1373.  Sterne. — Exhaust  silencer. 


Appendix  II  503 


NO. 


1457.  Wirth  (Bernstein). — Improvements  in  apparatus  for,  and  the  method 
of,  producing  motive  power  by  the  explosion  of  coal  or  carbon  dust 
and  air. 

2088.     Rodgerson — Improvements  in  gas  motor  engines. 

2135.  Henderson  (Eteve  &  Braam) — An  improved  petroleum  or  hydro- 
carbon engine. 

2289.  Rockhill. — Improvements  in  or  relating  to  brakes  for  gas  or  other 
engines. 

2715.     Woodhead — Improvements  in  gas  motor  engines. 

2854.     Clayton.  — Improvements  in  gas  motor  engines. 

2933.     Fielding. — Improvements  in  gas  motor  engines. 

3039.     Atkinson.  —  Improvements  in  gas  engines. 

3495.     Cobham  &  Gillespie. — Improvements  in  gas  engines. 

3537.     Holt&  Crossley. — An  improved  apparatus  for  starting  gas  motor  engines. 

3758.  Griffin — Improvements  in  piston-rod  stuffing-boxes  for  gas  motor 
engines. 

3893.     Holt.  —  Compressing  pumps  for  gas  motor  engines. 

3986.     Johnson  (Deboutteville  &  Malandin) Improvements  in  gas  engines. 

4391.     Williamson  &  others. — Improvements  in  gas  motor  engines. 

4591.      Munden Improvements  in  gas  motor  engines. 

4639.      Pollock Improvements  in  valves  for  gas  engines. 

4736.     Wirth  (Sohnlein) Improvements  in  gas  engines. 

4776.  Spence. — Improvements  in  gas  engines. 

4777.  Crossley Gas  motor  engines. 

4880.     Weatherhogg.  — Improvements  in  gas  motor  engines. 

5007.      Hill  &  Hill. — Improvements  in  engines  worked  by  gas  or  vapour. 

5302.  Johns  &  Johns. — Improvements  in  rotary  gas  engines. 

5303.  Johns  &  Johns Improvements  in  rotary  gas  engines  and  other  rotary 

motors. 

5412.     Dewhurst. — Improvements  in  and  connected  with  gas  engines. 
5435.     Park — Improvements  in  rotary  engines  and  pumps. 

5641.     Butcher Improved  igniting  valve  for  gas  engines. 

5797.     Linford  &  Piercy. — Improvements  in  gas  engines. 

6597.     Shann.— Improvements  in  the  machinery  for  obtaining  rotary  motion 

by  the  action  of  two  forces  on  different  cranks. 
6652.     Johnson.— Improvements  in  apparatus  for  carburetting  air. 

6662.     Wiegand Improvements  in  gas  engines. 

6784.     McNeill,— Improvements  in  tramway  locomotives  driven  by  gas. 

7284.     King Improvements  in  gas  motor  engines. 

7288.     King. — Improvements  in  gas  motor  engines. 
8211.     Holt.  —Compound  gas  motor  engine. 

8232.     Sombart Improvements  in  gas  engines. 

8489.     Green.  —Improvements  in  gas  motor  engines,  and  in  the  means  or 

method  of  supplying  them  with  gas. 


504  The  Gas  Engine 


NO. 


8565.     Rogers. — Improvements  in  gas  engines. 

8579.      Shaw.— Improvements  in  gas  motor  engines. 

8637.     Crossley. — Improvements  in  Otto  and  other  gas  engines. 

8960.     Ainsworth. — Improvements  in  gas  engine  cylinders. 

9001.      Guthrie — Improvements  in  gas  engines. 

9112.      Groth  (Daimler).  —  Improvements  in  gas  or  oil  motors. 

9167.     Williamson  and  others Improvements  in  or  relating  to  valves  for  gas 

motor  engines. 

9544.     Magee.—  Improvements  in  gas  engines. 
9645.     Welch  &  Rapier. — Improvements  in  gas  engines. 
9949.     Capitaine  (Eenz  &  Co.). — Improvements  in  gas  motors. 
10062.     Norrington.  — Improvements  in  means  for  assisting  velocipedes  and  gas 

engines  to  start. 

10364.     Wallace Improved    apparatus    for   converting    reciprocating    recti- 
linear motion  into  rotary  motion. 
10483.      Guthrie — Improvements  in  caloric  engines. 
11086.     Butterworth — Improvements  in  motors  worked  by  combustible  gas 

or  vapour. 
11361.     Justice  (Backeljau) — Improvements  in  and  connected  with  automatic 

gas  motors. 
11576.     Griffin — Improvements  in  apparatus  for  lubricating  gas  and  other 

motor  engines  and  machines. 
11578.     Crossley — Improvements  in  gas  motor  engines. 

1175°-     Douglas Improvements  in  gas  engines. 

11837.     Clark  (Hopkins). — Improvements  in  gas  engines. 

12201.     Griffith. — Improvements  in  and  connected  with  gas  engines. 

12264.     Davy. — Improvements  in  gas  engines. 

12312.     Brine — Improvements  in  gas  engines. 

12318.     Dougill — Improvements  in  gas  motor  engines. 

12431.     Purnell — An  improvement  in  gas  motor  engines. 

12603.     Hill    &     Hill — Improvements     in    engines     worked     by    gas    or 

vapour. 

12640.     Tellier. — Motive  power  by  gas,  steam,  combustible  fluids,  &c. 
12714.     Redclie  (Murray).— Improvements  in  gas  engines. 
12776.     Wilson — Improvements   in    the    construction    of  tramway    engines 

driven  by  gas. 

13221.     Andrew — Improvements  in  gas  motor  engines. 
13283.     Redfern  (McDonough) — Improvements  in  gas  engines. 
13573-     Fairfix — Improvements  in  rotary  and  reciprocating  engines.- 
13776.     Parker — Improvements  in  gas  motor  engines. 
J3935-     Lawson — Improvements  in  gas  engines  for  pumping  water  and  for 

other  uses. 

14311.     Griffin — Improvements  in  gas  motor  engines. 
14341.     Browett — Improvements  in  gas  motor  engines. 


Appendix  II  505  • 


N'O. 


14512.  Pr entice  &  Prentice — Apparatus  for  igniting  gas  engine  charges  at 

starting. 

14765.  McGillivray.— Improvements  in  gas  engines. 

15248.  Johnson  (Deboutteville  &  Malandin). — Improvements  in  carburetters. 

15311.  Holt  &  Crossley — Compound  gas  motor  engine. 

15312.  Holt — Gas  motor  engine. 

15633.  Newton. — Improvements  in  gas  motor  engines. 

16131.  Benier — Improvements  in  hot  air  engines. 

16404.  Atkinson — Improvements  in  gas  engines. 

16634.  Muller  and  others — Improvements  in  gas  engines. 

16698.  Turner. — Improvements  in  gas  motor  engines. 

16893.  Regan. — Improvements  in  or  connected  with  electric  igniting  appa- 
ratus for  gas  engines. 

16947.      Imray  (Barnes  &  Banks) Gas  motor  for  tramcar. 

1885. 

610.     Johnson  (Lenoir) — Improvements  in  or  connected  with  gas  engines. 
848.     Myers. — Improvements  in  gas  motor  engines. 
1218.      Pinkney. — Improvements  in  governors  for  gas  engines,  steam  engines, 

and  compressed-air  engines. 

1363.      Simon — An  improved  construction  and  arrangement  of  gas  engine. 
1424.     Asher  &  Buttress — A  new  or  improved  method  of  obtaining  motive 

power  by  the  explosive  combination  of  substances. 
1478.     Williamson,  King  &  Ireland. — Improvements  in  ignition  apparatus 

for  gas  motors. 
1581.     Kempster,  jun.  —  An  improved   motor  driven   by   the   explosion   of 

hydrocarbon  vapour. 

1700.     King Improvements  in  gas  motor  engines. 

1703.     Wright  &  Charlton — Improvements  in  heat  motors,  such  improve- 
ments   relating   to    petroleum   and   other    hydrocarbon   explosive 

engines. 

2712.     Atkinson Improvements  in  gas  engines. 

3199.     Beechey. — Improvements  in  gas  motor  engines. 

3414.     Spiel Improvements  in  petroleum  and  gas  engines. 

3471.     Pope. — Improvements  in  gas  engines. 

3747.     Holt. — Regulator  for  supply  of  gas  to  motor  engines. 

3785.     Atkinson. — Improvements  in  gas  engines. 

3971.      Mackenzie. — Improvements  in  gas  engines. 

4315.     Daimler.— Improvements  in  motor  engines  worked  by  combustible 

gases,  or  petroleum  vapour,  or  spray. 
4684.     Garrett.— Improvements  in  motors  worked   by  combustible  gas  or 

vapour. 
5519.     Bickerton.  -  Improvements  in  gas  regulators  for  supplying  gas  to  gas 

motors. 


506  The  Gas  Engine 


Andrew.  —  Improvements  in  gas  motor  engines. 

5971.     Mills.— Improvements  in  gas  motor  engines. 

6047.  Rigg.— Improvements  in  engines  worked  by  elastic  or  non-elastic 
fluids,  or  by  the  explosion  of  mixed  gases  ;  applicable  also  to  appa- 
ratus for  pumping. 

6565.      Weatherhogg Improvements  in  gas  motor  engines. 

6763.     McGhee  &  Magee.— Improvements  in  gas  motor  engines. 

6880.      Macgeorge Improvements  in  and  relating  to  gas  engines. 

6990.     Campbell. — Improvements  in  gas  engines. 

7104.  Warsop  &  Hill. — An  improved  apparatus  for  igniting  the  gas  or  ex- 
plosive mixture  in  gas  motor  engines. 

7500.     Capitaine  &  Briinler — Improvements  in  gas  engines. 

7581.  Capitaine  &  Briinler.—  Improvements  in  the  production  of  a  com- 
pressed gaseous  compound  for  use  in  gas  motors  and  for  other 
purposes,  and  apparatus  therefor. 

7920.     Dawson. — Improvements  in  gas  engines. 

7929.     Newton.  —  Improvements  in  gas  motor  engines. 

8134.     Crossley. — An  improved  gas  engine. 

8160.     Wordsworth  &  Wolstenholme — Improvements  in  gas  engines. 

8411.     Humes — Improvements  in  hydro-carburetted  air  engines. 

8583.  Newton Improvements  in  gas  motor  engines. 

8584.  Treeton Improvements  in  or  relating  to  gas  engines. 

8897.      Sturgeon. — Improvements  in  gas  engines. 

9801.     Colton  (Hartig). — An  improved  gas  engine. 

10227.  Priestman  &  Priestman, — Improvements  in  the  construction  and 
working  of  motor  engines  operated  by  the  combustion  of  benzoline 
or  other  liquid  hydrocarbons. 

10401.     Justice  (Hale).— Improvements  in  gas  engines. 

10786.  Daimler. — Improved  vehicle  propelled  by  a  gas  or  petroleum  motor 
engine. 

11290.  Redfern  (Smyers) — Improvements  in  gas  engines  or  engines  actuated 
by  the  explosion  or  combustion  of  mixed  gas  or  vapour  and  air. 

11294.  Clark  (The  Economic  Motor  Company,  Incorporated).— Improve- 
ments in  gas  engines. 

11422.     Magee — Improvements  in  gas  engines. 

11555.     Cattrall  &  Storet. — Improvements  in  regulators  for  gas  engines. 

11558,     Gillott.  —  Improvements  in  gas  motors. 

11933.  Abel  (Gas-Motoren-Fabrik  Deutz).— An  improvement  in  the  slides 
and  passages  of  gas  motor  engines. 

12424.     Southall. — An  improvement  in  gas  motor  engines. 

12483.  Clark  (The  Economic  Motor  Company,  Incorporated) Improve- 
ments in  gas  engines. 

12896.     Schiltz — Improvements  in  gas  and  petroleum  engines. 

13163.     Groth  (Daimler) — Improvements  in  gas  and  oil  motive  power  engines. 


Appendix  II  507 


NO. 


I33°9-     Dinsmore — Improvements  in  rotary  air  and  gas  motor  engines. 
13623.      Royston — Improvements  in,  and  in  connection  with,  motive  power 

engines  actuated  by  the  combustion  of  a  mixture  of  gas  or  vapour 

and  atmospheric  air. 
14394.     Nash — Improvements  in  liquid  fuel  vapour  engines  and  method  of 

operating  the  same. 
14574.     Black. —Improvements  in  the  construction  of  steam  and  other  motive 

power  engines  of  the  horizontal  and  incline  and  vertical  table  class. 
15194.     Burgh  and  Gray — Improvements  in  motors  actuated  by  the  expansion 

of  gases  resulting  from  the  combustion  of  fuel  in  the  motor. 
15243.     Atkinson. — Self-starting  valve  for  gas  engines. 
15475.     Von  Ruckteschell. — An  improved  explosion  engine. 
15525.     Ashby — Improvements  in  gas  engines. 
15710.     Johnson  (Deboutteville  &  Malandin).  —  Improvements  in  governors  or 

regulators  for  gas  and  other  motive  power  engines. 
15737.     Rogers. — Improvements  in  gas  engines. 
15845.      Bickerton — Improvements  in  gas  motor  engines. 

15874.  Wilcox Improvements  in  gas  engines. 

15875.  Wilcox Improvements  in  gas  engines. 

15876.  Wilcox — Improvements  in  gas  engines. 

15936.     Wimshurst — An  improved  method  of  equalising  the  power  given  off 
by  gas  or  other  engines  or  motors. 

1886. 

II.     Johnson  (Deboutteville  &  Malandin). — Improvements  in  gas  engines. 
207.     Butterworth. — Improvements  in  motors  worked  by  combustible  gas 

or  vapour. 

478.     P'airweather  (Babcock) — Improvements  in  air  or  gas  engines. 
493.     Nash. — Improvements  in  gas  engines. 

665.     Magee. Improvements  in  gas  motor  engines. 

942.      Brine — Improvements  in  gas  engines. 

1394.     Priestman  &  Priestman Improvements  in  motor  engines  operated  by 

the  combustion  of  liquid  hydrocarbon. 
1433.     McGhee — Improvements  in  gas  engines. 

1464.      Humes Improved    means    for    mixing   and    igniting    combustible 

charges  operating  liquid  hydrocarbon  engines. 
1696.     Welch  &  Rook — An  improved  gas  engine. 
1797.     Shillito  (Capitaine). — An  improved  method  and  means  for  cooling  the 

cylinders  of  gas,  petroleum,  hot  air,  and  similar  motors. 
1958.     Haddan  (Jonasen). — Improvements  in  gas  motors. 
2140.     Capitaine  &  Brlinler — Improvements  in  oil,  petroleum,  naphtha,  and 

similar  motors. 
2174.     Skene.— Improvements  in  gas  engines. 


$o8  The  Gas  Engine 


NO. 


2272.     Leigh  (Spiel) — Improved  supply  valve  gear    for    petroleum  or  gas 

engines. 

2447.      Shaw — Improvements  in  the  construction  of  gas  engines. 
2653.      Boulton  &  Perrett. — Combined  steam  and  gas  engines. 
2993.      Mil  burn  &  Hannan Improvements  in  motors  worked  by  combustible 

gas  or  vapour. 
3010.      Deacon. — Improvements  in  and  in   connection  with    motive    power 

engines  actuated  by  pressure  due  to  heat  of  combustion. 

3402.      Fielding A  gas  motor  engine. 

3473.  Davy — An  improvement  in  gas  engines. 
3522.  Atkinson — Improvements  in  gas  engines. 
4234.  Niel — Improvements  in  gas  engines. 

4460.      Dawson Improvements  in  gas  engines. 

4785.      Hutchinson — Improvements    in    engines   actuated   by    the   thermo- 

dynamic  energy  of  petroleum  and  similar  combustible  fluids. 
4881.     Justice  (Taylor). — Improved  combined  gas  engine  and  fluid  pump. 
5597.      Humes — Improved  means  for  preventing  'back  ignition'  in  hydro- 
carbon engines. 

5665.      Bernardi — Improvements  in  and  relating  to  gas  engines  or  motors. 
5789.     Benz — Improvements  in  gas  motors  for  wheeled  vehicles  and  in  their 

application  thereto. 

5804.     Abel. — Improvements  in  gas  motor  engines. 
6161.     Redfern  (Gardie).-  An  improved  motor,  and  apparatus  for  generating 

gas  therefor. 

6165.     Leigh  (Spiel).  — Improvements  in  petroleum  and  gas  engines. 
6551.     Wright  &  Charlton  Wright — Improvements  in  petroleum  and    such 

like  engines. 

6612.     Gillespie. — Improvements  in  gas  motor  engines. 
6670.     Nash. —  Improvements  in  construction  and  method  of  operating  gas 

engines. 

7427.     Rollason. — Improvements  in  gas  engines. 
7658.     Nixon.— Improvements  in  gas  engines   having   two   pistons   in  the 

same  cylinder. 

7936.     Butterworth.  — Improvements  in  motors  worked  by  combustible  gas. 
8210.     Roots. — A  petroleum  engine. 

8436.  Weatherhogg. — Improvements  in  petroleum  and  similar  engines. 
9563.  fielding.— -Ignition  apparatus  for  gas  motor  or  oil  motor  engine. 
9598.  Johnson  (Deboutteville  &  Malandin). — Improvements  in  apparatus 

for  carburetting  air. 

9866.     Stuart. — Improvements  in  petroleum  and  other  explosive  engines. 
10332.      Boys  &  Cunynghame.— Reducing  or  preventing  noise  of  escaping  gas 

or  vapour. 
10480.     Schiltz. — Improvements  in  or  connected  with  petroleum  motors  or 

engines  worked  with  liquid  fuel. 


Appendix  II 


509 


NO. 

11269.  Humes. — Improvements  in  or  applicable  to  motor  engines  operated 
by  the  combustion  of  fluid  hydrocarbon. 

11285.     Crossley. — Improvements  in  valves  for  gas  and  oil  motor  engines. 

11576.     Bolt. — Improvements  in  gas  engines. 

12068.  Hutchinson  and  London  Economic  Motor  and  Gas  Engine  Co.  — Im- 
provements in  motor  engines  worked  by  combustible  gases  or 
petroleum  vapour  or  spray. 

1 2 1 34.  Butterworth  &  Butterworth.  —  Improvements  in  engines  in  which  power 
is  obtained  by  the  ignition  and  expansion  of  a  combustible  mixture. 

12368.      Rollason. — Improvements  in  gas  or  vapour  engines. 

12640.  Sutclifife. — Improvements  in  utilising  the  waste  heat  of  gas  and  com- 
bustion explosive  motor  engines  for  heating  water. 

12912.     Clerk. — Improvements  in  gas  motors. 

13229.  Humes. — Improvements  in  and  connected  with  motor  engines 
operated  by  the  combustion  of  fluid  hydrocarbon. 

13517.  Maccallum. — Improvements  in  and  relating  to  the  propulsion  of  navi- 
gable vessels. 

13655.     Rockhill. — Improvements  relating  to  flywheel  guards. 

13727.     Newton  (Murray). — Improvements  in  the  construction  of  gas  engines. 

14034.  Daimler. — Apparatus  for  effecting  marine  propulsion  by  gas  or 
petroleum  motor  engines. 

14578.  McGhee.— An  improved  gas  motor  engine,  specially  applicable  for 
use  with  mangling  machines. 

15307.      Robson. — Improvements  in  gas  engines. 

15319.  Stuart  &  Binney. — Improvements  in  gas,  petroleum,  and  other  hydro- 
carbon explosive  engines  or  motors. 

15327.     Taylor. — An  improved  gas  motor  engine. 

15472.      Southall An  improvement  in  gas  motor  engines. 

15507.  Wordsworth  &  Wolstenholme. — Improvements  in  gas  or  other 
hydrocarbon  motors. 

1 5507 A.  Wordsworth  &  Wolstenholme.  —Improvements  in  gas  or  other  hydro- 
carbon motors. 

1 5764.     Griffin Improvements  in  apparatus  for  automatically  shutting  off  the 

gas  supply  of  gas  motor  engines. 

15955.  Hearson. — Improvements  in  arrangements  for  utilising  the  vapour  of 
volatile  liquid  hydrocarbons  for  actuating  motive  power  engines. 

16779.  Priestman  &  Priestman. —Improvements  in  the  construction  and 
working  of  hydro-carburetted  air  engines,  and  in  apparatus  ap- 
plicable thereto. 

1887. 

8.  Turnock.— Improvements  in  apparatus  for  converting  reciprocating 
into  rotary  motion,  and  in  the  application  of  such  apparatus  to  steam 
and  other  fluid  pressure  engines. 


5  ic  The  Gas  Engine 


NO. 


125.     Sterry  &;  Sterry. — Improvements  in  explosive  gas  engines. 

516.     Newhall   &    Blyth. — Improvements   in   gas    and   other   hydrocarbon 

engines. 
847.     Abel  (The  Gas-Motoren-Fabrik  Deutz).— Igniting  apparatus  for  gas 

engines. 

888.     Hosack.  —Improvements  in  internal  combustion  « heat '  engines. 
1168.     Charter,  Gait  &  Tracy.  — Improvements  in  gas  engines. 
1189.     Abel  (The  Gas-Motoren-Fabrik   Deutz).  —Improvements  in  gas  motor 

engines. 

1262.      Benier. — Improvements  in  hot  air  engines. 
1266.     Adam. — Improvements  in  gas  and  other  hydrocarbon  engines. 
1454.      Priestman  &  Priestman. — Improvements  in  the  construction  and  work- 
ing of  hydro  carburetted  air  engines. 
1986.     Pinkney.  —Improvements   in    hammering,    stamping,    punching,    and 

other  like  machinery  actuated  by  explosive  gaseous  mixture. 
2194.     Haddan  (Gavillet  &  Martaresche).— Improvements  in  gas  engine. 
2236.     Bamford.  —  Improvements  in  lubricators  used  for  gas  engines  and  other 

purposes. 
2368.     Thomas. — Improvements  in  engines  driven  by  gas,  steam,  petroleum, 

and  the  like. 
2520.     Browett  &  Lindley. — Improvements  in  motor  engines  worked  by  gas 

or  hydrocarbon. 

2631.     Tellier. — Improvements  in  tramway  and  railway  locomotives. 
2783.     Knight. — Improvements   in    engines   worked    by  the  heavier   hydro- 
carbons. 
3109.     Spiel.  —  Improvements  relating  to  engines  or  motors  chiefly  designed 

to  be  driven  by  means  of  carburetted  air. 
3934-     Griffin. — Improvements  in  the  arrangement  and  construction  of  gas 

motor  engines. 
4160.     Beechey.  —  Improvements  in  gas-bags  or  apparatus  for  regulating  the 

supply  of  gas  to  gas  engines. 

4403.     Ross  &  McDowall.  --Improvements  in  rotary  engines  and  pumps. 
4511.      Ridealgh. — Improvements  in  gas  engines. 
4564.     Sington. — Improvements  in  and  relating  to  the  traction  or  propulsion 

of  tramcars  and  road  vehicles  by  means  of  gas  and  similar  engines  or 

motors. 
4757-     Casper  (Tavernier).  —  Improvements  in  gas  and  other  engines  operated 

by  explosive  mixtures, 
4843.     Stevens. —Improvements     in     combined     gas    and    compressed    air 

engines. 

4923.     Sturgeon. — Improvements  in  certain  gas  engines. 
4940.     Wallwork.  —  Improvements    in    self-acting    mechanism    or   apparatus 

for     supplying    lubricant     to    parts    of    gas    engines    and    other 

machinery. 


Appendix  II  511 


NO. 


5095.     Johnson  (La  Soeiete  des  Tissages  et  Ateliers  de  Construction  Diede- 
richs). — Improvements  in  gas  engines. 

5336.     Bernhardt. — Improvements   in   regulating  apparatus   for   gas  motor 
engines. 

5485.     Hargreaves.— Improvements  in  and  connected  with  internal  combus- 
tion thermo-dynamic  engines. 

5833.     Crossley. — A    combined    gas    motor    engine   and    dynamo   electric 
machine. 

5951.     Priestman  &  Priestman.  —  Improvements  in  motor  engines  operated 
by  the  combustion  of  liquid  hydrocarbon. 

5981.      Korting.  —  Improvements  in  gas  motors. 

6501.      Dawson.  —  Improvements  in  engines  worked  by  explosive  mixtures. 

7350.      Faber.  —  Improvements  in  gas  motors. 

7677.      Davy. — An  improved  gas  engine. 

7771.     Wastfield. — Improvements  in  and  relating  to  gas  engines. 

7925.     Wallwork  &  Sturgeon. — Improvements  in  gas  engines. 

8818.     Beechey.—  Improvements  in  gas  motor  engines. 

9111.     Haddan    (Archat).  —  Improvements   in   gas,    petroleum,    and   other 
hydrocarbon  engines. 

9717.      Ducretet. — Improvements  relating  to  apparatus  for  filtering  or  purify- 
ing oil  in  connection  with  gas  and  petroleum  engines. 
10176.      Hahn. — Improvements  in  gas  motors. 
10202.     H.  C.  Bull  &  Co.  and  H.  C.  Bull.— Improvements  in  and  connected 

with  gas  motors. 
10360.     Dougill.  —  Improvements  in  gas  motor  engines. 

10460.     Griffin.  —  Improvements  in  double  cylinder  gas  motor  engines. 

11255.     Justice  (Hale).-  Improvements  in  gas  and  pumping  engines. 
11345.     Lindley  &  Browett.  —  Improvements  in  gas  motor  engines. 

11444.     Abel  (The  Gas-Motoren-Fabrik  Deutz).— Improvements  in  igniting 
apparatus  for  gas  motor  engines. 

11466.     Wordsworth. — Improvements  in  gas  or  other  hydrocarbon  motors. 

11503.     Abel    (The  Gas-Motoren-Fabrik   Deutz).— Improvements  in  motor 
engines  worked  by  combustible  gas,  vapour,  or  spray  and  air. 

11567.     Niel  &  Bennett. — Improvements  in  hydrocarbon  engines. 

1 1678.      McGhee  &  Burt. — A  new  or  improved  combined  mincing  machine  and 
gas  motor  engine. 

11717.     Embleton. — Improvements  in  gas  motor  engines. 

11911.     Atkinson. — Improvements  in  gas  engines. 

12187.     Abel  (The  Gas-Motoren-Fabrik  Deutz).  —  Improvements  in  gas  motor 
engines. 

12432.     Priestman  &  Priestman.— Improvements  in  or  applicable  to  motor 
engines  operated  by  the  combustion  of  hydrocarbon  vapour. 

12591.     Lane.— Improved  method  of  applying  or  utilising  compressed  com- 
bustible gases  for  the  production  of  motive  power. 


5 1 2  The  Gas  Engine 


NO. 


12592.  Hearson.  —Improvements  in  and  connected  with  the  vaporisation  of 
volatile  liquid  hydrocarbons,  and  the  utilisation  of  the  vapour 
thereof  for  actuating  motive  power  engines,  and  apparatus  or 
arrangements  for  those  purposes. 

12696.      List,  List,  &  Kosakoff.— Improvements  in  petroleum  engines. 

12749.      Charter,  Gait,  &  Tracy.— Improvements  in  gas  'engines, 

12863.      Korting Improvements  in  gas  engines. 

1 3436.      Lea.  —  Improvements  in  gas  engines. 

13555.      Knight Improvements  in  engines  worked  by  mineral  oils. 

13916.      Davy Improvements  in  gas  engines. 

14027.     Barker Improvements  in  gas  engines. 

14048.      Middleton.— A  new  or  improved  gas  motor  engine. 

14269.  Ilutchinson Improvements  in  and  relating  to  utilising  the  chamber 

or  space  between  the  cylinder  and  jackets  of  engines  or  motors  for 
the  purpose  of  vaporising  oil  in  connection  with  steam,  gas,  oil,  or 
other  engines  or  motors  using  heat  as  a  source  of  power. 

14952.     Schmid  &  Bechfeld. — Improvements  in  gas  engines. 

15010.     Crossley  &  Anderson. — Ignition  apparatus  for  gas  or  oil  motor. 

15598.  Butler. — Improvements  in  hydrocarbon  motors,  and  in  the  method 
of  their  application  for  the  propulsion  of  tricycles  and  other  light 
vehicles. 

15658.     Davy Improvements  in  gas  and  other  engines. 

16029.     Williams Improvements  in  gas  motor  engines. 

16144.     Williams.  — Improvements  in  gas  motor  engines. 

16257.     Ravel  &  Breittmayer — Improvements  in  and  relating  to  gas  engines. 

16309.      Sturgeon Improvements  in  gas  engines. 

17108.  Abel  (The  Gas-Motoren-Fabrik  Deutz) — Improvements  in  motor 
engines  worked  by  combustible  gas. 

17353.  Wall  work  &  Sturgeon. — Improvements  in  apparatus  for  governing  the 
speed  of  gas  engines. 

17686.  Bickerton. — Improvements  in  the  method  of,  and  apparatus  for,  start- 
ing gas  engines. 

17896.  Abel  (The  Gas-Mctoren-Fabrik  Deutz) — Apparatus  for  heating  the 
igniting  tubes  of  gas  motor  engines. 

1888. 

270.  Priestman  and  another.  —  Improved  means  for  facilitating  the  starting 
of  hydrocarbon  engines,  and  for  regulating  the  ignition  of  the  in- 
flammable charges  whereby  same  are  operated. 

512.     Sington.--  Improvements  in  gas,  petroleum,  and  similar  engines. 

688.     Abel    (The  Gas-Motoren-Fabrik  Deutz) — Improvements  in  igniting 

apparatus  for  gas  motor  engines. 
1336.     Imray.— Improvements  in  apparatus  for  starting  tramway  cars. 


Appendix  II  513 

Blessing.  —Improvements  in  gas  and  other  hydrocarbon  engines. 

Crossley. —Compound  gas  or  oil  motor  engine. 

Butler. — Improvements  in  hydrocarbon  motors. 

Butler. — Improvements  in  hydrocarbon  motors. 

Quack. — Improvements   in  motor  engines  worked   by  combustible 

gas  or  vapour  and  air. 

Johnson  (La  Societe  Salomon). — Improvements  in  gas  engines. 
Johnson    (Deboutteville   &    Malandin). — Improvements    in   starting 

gear  for  gas  engines. 

Oechelhaeuser. — Improvements  relating  to  gas  engines. 
Abel  (The  Gas-Motoren-Fabrik    Deutz). — Improvements   in   motor 

engines  worked  by  combustible  gas  or  vapour  and  air. 
Abel  (The  Gas-Motoren-Fabrik  Deutz). — Improvements  in  igniting 

apparatus  for  gas  or  oil  motor  engines. 
McGhee  &  Burt. — Improvements  in  gas  motor  engines. 
Rollason  &   Hamilton — Improvements  in  and  connected  with  gas 

and  vapour  engines. 
Crossley.  — Improvements  in  igniting  apparatus  for  gas  and  oil  motor 

engines. 

Gase. — Improvements  in  the  mode  of  working  gas  engines. 
Turner  &  Brightmore — Improvements  in  the  application  of  com- 
pressed atmospheric  air  to  motors. 
Crossley. — An  improvement  in  valve  and  governing  gear  for  gas  or 

oil  motor  engines. 
Wilson. — Improvements  in  or  pertaining  to  combined  arrangements 

of  gas  engines  and  gas  producers. 
Lake  (Beuger). — Improvements  in  and  relating  to  ignition  apparatus 

for  gas,  petroleum,  or  other  engines  or  motors. 
Ta vernier  &  Casper. — Improvements  in  and  relating  to  gas  and  other 

engines. 
Humes. — Improvements  in  or  applicable  to  motor  engines  operated 

by  the  combustion  of  hydrocarbon  vapour. 
Abel  (The  Gas-Motoren-Fabrik  Deutz) An  improvement  in  motor 

engines  worked  by  the  combustion  of  spray  of  petroleum  or  other 

combustible  liquids. 

Rowden Improvements  in  motors  worked  by  gas  or   other  com- 
bustible bodies. 
Lake    (Spiel). — Improvements    in    and     relating     to     hydrocarbon 

engines. 

Gase. — Improvements  in  gas  engines. 
Thompson  (Durand).  —  Improvements  in  and  relating  to  engines  or 

motors,  and  to  the  production  of  carburetted  air  for  driving  ths 

same. 

L  L 


514  The  Gas  Engine 


NO. 


6468.  Korytyn ski.— Improvements  in  engines  designed  to  produce  motive 
power  through  the  consumption  of  inflammable  vapours  or  gas. 

6794.  Stitt. —Improvements  in  or  connected  with  mechanically  propelled 
lifeboats,  applicable  also  to  other  craft. 

7521.     Wordsworth.  — Improvements  in  gas  or  liquid  hydrocarbon  motors. 

7547.  Browett  &  Lindley.—  Improvements  in  motor  engines  worked  by 
gas  or  hydrocarbon. 

7893.  Schnell. — Improvements  in  motor  engines  actuated  by  a  mixture  of 
gas,  or  the  vapour  of  a  hydrocarbon  or  hydrocarbons,  and  atmo- 
spheric air, 

7927.  Stubbs. — Improvements  in  motor  engines  actuated  by  the  combus- 
tion of  mixtures  of  combustible  gas  and  air  and  the  vapour  of  a 
hydrocarbon  or  hydrocarbons,  or  other  combustible  mixtures. 

7934.      Southall.—  Improvements  in  gas  motor  engines. 

8009.     Nelson. — Improvements  in  hydrocarbon  engines. 

8252.  Johnston.  —  Improvements  in  motors  to  work  with  combustible  gas  or 
vapour. 

8273.  Kostovitz. — Improvements  in  and  relating  to  gas  and  hydrocarbon 
engines. 

8300.  Deboutteville  &  Malandin. — Improvements  in  starting  gear  for  gas 
engines. 

8317.     Altmann Improvements  in  petroleum  motors. 

9249.  Deboutteville  &  Malandin.  —Improvements  in  governors  for  gas 
engines  and  other  like  motors. 

9310.  Roots.  —  Improvements  in  gas  engines. 

9311.  Roots. — Improvements  in  hydrocarbon  engines. 

9342.     Aria  &  Chemin.— Process  for  treating  leather  pistons  to  render  same 

impervious  to  action  of  petroleum  and  heavy  oils. 
9578.  .  Dougill. — Improvements  in  gas  motor  engines. 

9602.  Abel  (Gas-Motoren-Fabrik  Deutz). — Improvements  in  valve  appa- 
ratus for  gas  and  oil  motor  engines. 

9691.     Knight. — Improvements  in  engines  worked  by  mineral  oils. 
9705.     Rowden. — An  improved  motor  actuated  by  the  explosions  of  mixtures 

of  inflammable  gases  or  vapours  and  atmospheric  air. 
9725.     Middleton. — Improvements  in   flying   machines,   and  apparatus  for 

propelling  the  same. 

10165.     Purnell. — An  improved  gas  motor  engine. 
10350.     Nash. — Improvements  in  gas  engines. 
10462.     Williams. — Improvements  in  mechanism  for  regulating  the  supply  of 

gas  or  other  fluid  to  gas  or  similar  engines. 
10494.     Hall. — Improvements  in  motor  engines  operated  by  the  combustion 

of  explosive  mixtures  of  fluids. 

10067.  Binney  &  Stuart. — Improvements  in  petroleum  and  other  hydrocarbon 
explosive  engines  and  motors. 


Appendix  II  515 


NO. 


10748.     Campbell. — Improvements  in  gas  motor  engines. 

10980.     Hargreaves.— Improvements  in  internal  combustion  thermo-motors. 

10983.  Piers. — An  improved  form  of  engine  adapted  to  tramcars  and  loco- 

motives. 

10984.  Piers. — An  improved  method  for  starting   gas   engines  and  hot  air 

and  petroleum  engines,  particularly  when  such  engines  are  applied 

to  tramcars  or  locomotives. 

11067.      Roots. — Improvements  in  hydrocarbon  or  petroleum  engines. 
11161.     Morris  &  Wilson.  —  Improvements  in  apparatus  for  the  generation  of 

gas  from  hydrocarbon  oils. 

1 1 242.      Barker.  — Improvements  in  gas  engines. 
11614.      Purchas  &  Friend. — Improvements  in  hydrocarbon  motors. 
12361.      Hargreaves.  —  Improvements  in  internal  combustion  thermo-motor. 
12399.     Charon. — Improvements  in  gas  motors  with  variable  expansion. 
13414.      Boult  (Larrivel  &  Aeugenheyster). — Improvements  in  gas  motor. 
14076.      Stuart  &  Binney. — Improvements  in  hydrocarbon  explosive  engines. 
14248.      Crossley,  Holt  &  Anderson. — An  improvement  in  gas  motor  engines. 
14349.     Abel  (The  Gas-Motoren-Fabrik  Deutz).—  Igniting  apparatus  for  gas 

and  oil  motor  engines. 
14401.     Hearson. — Improvements  in  motive  power  engines  actuated  by  the 

firing  of  inflammable  gas  or  vapour  in  admixture  with  air. 
14614.     Royston. — Improvements  in  and  connected  with  internal  combustion 

heat  engines. 
14831.     Williams. — Improvements  in  mechanism  for  governing  the  speed  of 

gas  and  similar  motor  engines. 
15158.      Richards. — Improvements  in  hydrocarbon  engines,  partly  applicable 

to  other  motor  engines. 
15448.     Thompson  (Regan). — Improvements  in  or  relating  to  gas  engines. 

15840.  Boult  (Capitaine).  — Improvements  in  or  relating  to  gas  motors. 

15841.  Boult  (Capitaine). — Improvements  in  or  relating  to  igniting  apparatus 

for  gas  motors. 

15845.  Boult  (Capitaine). — Improvements  in  gas  motors. 

15846.  Boult  (Capitaine). — An  improved  friction  clutch  or  coupling  specially 

applicable  to  gas  motors. 

15858.  Jensen  (Weilbach).  —  Improvements  in  apparatus  for  braking  and  re- 
starting of  rotating  axles  or  shafts  of  tramcars,  gas  engines,  and 
other  machinery. 

15882.      Roots. — Improvements  in  or  connected  with  petroleum  engines. 

16057.  Lindley  &  Browett. — Improvements  in  liquid  hydrocarbon  motor 
engines. 

16183.     Simon. — An  improvement  in  or  connected  with  gas  engines. 

16220.      Roots. — Improvements  in  gas  engines. 

16268.      Lalbin. — Improvements  in  and  relating  to  gas  engines. 

16605.     Menzies.  — Improvements  in  and  relating  to  piston  packing  rings. 

L  L  2 


516  The  Gas  Engine 

NO. 

17167.      Korting Improvements  in  gas  and  petroleum  engines. 

17413.     Crossley  &  Anderson.— Improvements  in  igniting  apparatus  for  gas  or 

oil  motor  engines. 

18377.      Shaw. — Improvements  in  gas  and  other  explosive  engines. 
18761.      Hargreaves. — Improvements  in  internal  combustion  thermo- motors. 
19013.      Pinkney Improvements  in  gas  motor  engines. 

1889. 
I2i.      Boult    (Capitaine). — Improvements    in    or    relating    to    distributing 

mechanism  for  gas  motors. 
441.      Paton.  — Improvements   in    appliances    for   starting   gas  and  similar 

engines. 

708.     Taylor. — An  improved  gas  motor  engine. 
875.      Repland  (Niel).—  Improvements  in  gas  engines. 
1603.     Tavernier. — Improvements  in  and  relating  to  engines. 
1957.      Publis. — Improvements  in  gas  motors. 
2144*     Piers. — The  application  of  gas  and   petroleum  and   like  engines  to 

locomotive  and  other  intermittent  work. 
2637.      Miller. — Improvements  in   and   relating   to   petroleum,    oil,  vapour, 

gas,  and  other  explosive  power  engines. 

2649.     Gardie. — An  improved  gas  engine  and  gas  generator  therefor. 
2760.     Hartley. — Improvements  in  apparatus  for  measuring  liquids. 
2772.     Smith. — Improvements  in  or  relating  to  the  starting  of  motive  power 

engines. 
3331.     Adams.— Improvements  in  engines  and  motors  actuated  by  products 

of  combustion. 

3525.     Pinkney. — Improvements  in  gas  engines. 
3820.     Williams.  — Improvements  in  gas  motor  engines. 
3887.     Imray  (Weilbach).  —  Improvements  in  brake  apparatus  for  revolving 

axles  or  shafts. 

3972.     Roots. — Improvements  in  gas  engines. 

4710.     Oechelhaeuser.  —Improvements  in  and  relating  to  gas  engines. 
4796.     Schimming. — Improvements  in,  and  apparatus  for,  superheating  steam 

and  applying  the  same  to  steam  engines. 
5072.     Southall. — Improvements  in  gas  or  oil  motor  engines. 
5165.     Lake. — Improvements  in  and  relating  to  gas  or  vapour  engines  for 

the  propulsion  of  ships  and  other  purposes.     (The   Secor   Marine 

Propeller  Company.) 
5199.     Millet.  —  Improvements  in  gas  and  other  fluid  pressure   engines  for 

terrestrial  and  aerial  propulsion. 
5301.     Theerman. — Improvements  in  motor  engines  operated  by  the  ignition 

of  explosive  mixtures  of  air  and  petroleum,  or  other   hydrocarbon, 

or  gas. 
5397-     Nelson  &.  McMillan. — Improvements  in  gas  motor  engines. 


Appendix  II  5^ 

NO. 

5616.  Abel  (Gas-Motoren-Fabrik  Deutz).—  Improved  mechanism  for  revers- 
ing the  motion  derived  from  a  motor  shaft,  applicable  to  the  motor 
engines  of  vessels  and'  vehicles,  and  for  other  purposes. 

6161.  Partridge  &  Brutton — Improvements  in  means  or  apparatus  for  start- 
ing gas  and  other  engines  and  machines. 

6296.     Banki  &  Csonka — Improved  valve  motion  for  gas  engines. 

6682.  Priestman  and  another — Improvements  in  or  applicable  to  motor 
engines  operated  by  the  combustion  of  hydrocarbon  vapour. 

6748.     Cordenons — Improvements  in  rotary  engines. 

6831.     Knight.— Improvements  in  engines  worked  by  mineral  oils. 

7069.  Tavernier  &  Casper.— Improvements  in  and  relating  to  engines 
worked  by  explosive  mixtures. 

7140.  Tellier.— Improvements  in  the  production  of  motive  power  by  the 
employment  of  gas,  steam,  and  vapour,  and  in  apparatus  employed 
therefor,  and  for  its  utilisation. 

7522.  Sumner.—  An  electric  ignition  apparatus  for  gas,  petroleum,  oil,  or 
combustible  vapour  engines. 

7533-  Sumner.  —An  ignition  apparatus  for  gas,  petroleum,  oil,  or  combusti- 
ble vapour  engines. 

7594.  Crowe  &  Crowe — Improvements  in  gas  and  hydrocarbon  motive 
engines. 

7640.     Lawson Improvements  in  gas  engines. 

8013.  Weatherhogg. — Improvements  in  and  relating  to  petroleum  and 
similar  engines. 

8778.     Imray  (Glaser). — Improvements  in  petroleum  motor  engines. 

8805.     Clerk. — Improvements  in  gas  engines. 

9203.  Butler  and  others — Improvements  in  and  connected  with  motors  in 
which  an  explosive  mixture  of  air  and  petroleum  is  used. 

9685.  Hunt  &  Howden.— Improvements  in  motors  actuated  by  combusti- 
ble gas  or  vapour. 

9834.     Roots Improvements  in  petroleum  or  hydrocarbon  engines. 

1 0007.     Daimler.—  Improvements  in  gas  and  petroleum  motor  engines. 
10286.      Rogers  &  Wharry. — Improvements  in  gas  engines. 
10634.     Bull.—  Improvements  in  petroleum  and  other  explosive  vapour  or  gas 
engines. 

0669.     Rowden. — Improvements  in  gas  motors. 

0831.  Leigh  (Forest  &  Gallice). — Improvements  in  compound  gas  or  petro- 
leum engines. 

0850.  Wastfield. — Improvements  in  or  relating  to  petroleum  or  hydro- 
carbon engines. 

1038.     White  &  Middleton. — Improvements  in  gas  engines. 

1162.  Williams. — An  improved  incandescent  tube  for  firing  the  explosive 
charges  of  gas  and  other  similar  motor  engines. 

11395.     Hartley.  — Improvements  in  hydrocarbon  or  petroleum  engines. 


5 1 8  The  Gas  Engine 

NO. 

11926.      Bull. — Improvements  in  vapour  gas  engines. 

12045.     Allison    (McNett).— Improvements    in    combined   gas   engines   and 

carburetters. 
12447.     Hoelljes. — Improvements   in,  and  in  the  method  of  operating,  gas 

engines. 
12472.     Thompson  (Covert).— Improvements  in  or  relating  to  gas  engines  or 

gas  motors. 
12502.     Lanchester.— Improvements  in  apparatus  for  governing  gas  and  other 

motive  power  engines. 
13572.      McAllen.— Improvements  in  gas  or  oil  motor  engines. 

14592.      Huntington Improvements  in  vehicles. 

14789.      Hargreaves Improvements    in    internal    combustion    regenerative 

thermo-motors,  some  of  which  said  improvements  are  applicable  to 

gas  and  hot  air  engines. 

14868.      Binney  &  Stuart. — Improvements  in  hydrocarbon  engines. 
14926.     Diederichs Improvements  in  or  connected  with  combustible  vapour 

engines. 

16202.     Green. — Improvements  in  gas  engines. 
16391.      Lindemann. — Improvements  in  gas  and  petroleum  engines. 
J6393-     Girardet Improvements  in  means  for  generating  and  utilising  gas 

or  vapour,  and  in  apparatus  therefor. 
16434.     Hamilton  &  Rollason — Improvements  in  and  connected  with  gas  or 

vapour  engines. 

17008.     Haedicke. — A  combined  gas  and  steam  motor  engine. 
17024.     Boult  (Rotten) — Improvements  in  petroleum  or  similar  motors. 

17295.     Niel  &  Janiot Improvements  in  gas  motors. 

17344.     Lowne Improvements  in  atmospheric  engines,  partly  applicable  to 

other  motive  power  engines. 
18746.     Abel  (The  Gas-Motoren-Fabrik  Deutz).— Improvements  in  igniting 

apparatus  for  gas  and  oil  motor  engines. 
18847.     Barnett  &  Daly — Improvements  in  gas  or  vapour  engines,  and  in 

electric  exploding  devices,  or  apparatus  for  such  engines. 
19868.     Lanchester — Improvements  in  gas  motor  engines. 
20033.     Lindley  &  Browett — Improvements  in  hydrocarbon  motor  engines. 
20115.     Ford Improvements  in  rotary  gas  engines,  parts  of  which  improve- 
ments are  applicable  to  other  engines. 

20161.     Duerr. — Improvements  in  gas  and  petroleum  motors. 
20166.      Frederking  and  another — Improvements  in  positive  motion  gear  for 

lift  valves. 
20249.     Crist  &  Covert — Improvements  in  gas  engines  and  igniters  for  the 

same. 

20482.     Atkinson Improvements  in  internal  combustion  heat  engines. 

20703.     Snelling — Improvements  in  rotary  engines  to  work  with  steam,  air, 

gas  and  other  fluids. 


Appendix  II  519 

NO. 

20892.     Abe    (The  Gas-Motoren-Fabrik   Deutz) Improved  apparatus    for 

regulating  the  speed  of  gas  and  oil  motor  engines. 

1890. 

1150.     Lindner. — Improvements  in  or  connected  with  petroleum  engines. 
1586.     Tavernier  &  Casper.— Improvements  in  or  relating  to  the  cylinders 

and  pistons  of  engines  operated  by  explosive  mixtures. 
1943.     Abel    (The  Gas-Motoren-Fabrik  Deutz) Improvements   in   motor 

engines  worked  by  oil  vapour. 
2207.      Scollay — Improved  means  for  regulating  the  admission  of  gas  and 

air  in  atmospheric  burners,  and  for  supplying  gas  engines. 
2^84.      La  Touche — Improvements  relating  to  hot  air  engines. 
2647.      Lake  (Beckfield  &  Schmid).—  Improvements  in  gas  engines. 
2919.      Grob  and  others. — Improvements  in  petroleum  engines. 
4164.     Abel  (Gas-Motoren-Fabrik    Deutz) Improvements   in    the    means 

and  apparatus  for  governing  gas  and  petroleum  engines. 
4362.     Binns. — Improvements  in  gas  motor  engines. 

4574.     Kaselowsky Improvements  in  gas  and  petroleum  motors. 

4823.     Otto. — Improvements  in  gas  or  oil  motor  engines. 

5005.      Baxter  (Hoist) — Improvements  in  gas  engines. 

5192.      Melhuish — Improvements  in  gas  and  petroleum  motors. 

5273.     Otto Improvements  in  gas  or  oil  motor  engines. 

5275.     Otto. — Improvements  in  petroleum  or  oil  motor  engine 

5479.     Lanchester. — Improvements  in  gas  motor  engines. 

5621.      King  (Connelly). — Improvements  in  or  connected  with  driving  gear 

for  giving  motion  to   tramcars   and   other   vehicles   propelled    by 

motors. 
5933.     Dheyne  and  others.  —Improvements  in  gas  engines  operated  by  gas 

generated  from  petroleum  or  other  liquid  hydrocarbons. 
5972.     Otto.  — Improvements  in  gas  and  oil  motor  engines. 
6015.     Hamilton.  — Improvements    in    gas    or    combustible    vapour  motor 

engines. 

6113.     Otto. Improvements  in  gas  and  oil  motor  engines. 

6217.     Griffin Improvements  in  apparatus  for  producing  combustible  gas 

for  gas  motor  engines  or  other  purposes. 

6407.     Dawson Improvements  in  gas  engines. 

6910.     Dorrington  &  Coates. —Improvements  in  gas  engines. 

6912.     Fielding. Improvements  in  gas  motor  engines. 

6990.     Butler. Improvements  in  motive  engines  operated  by  explosive  mix- 
tures of  petroleum  and  air. 
7 146.     Stuart  &  Binney Improvements  in  engines  operated  by  the  explosion 

of  mixtures  of  combustible  vapour  or  gas  and  air. 

7177.     Mewburn  (Prowell  and  others).— Combined  gas  and  compressed  air 
motors. 


52O  The  Gas  Engine 


NO. 


7626.     Johnson  (Lantsky). — Improvements  in  engines  or  motors  actuated  by 

products  of  explosion  or  combustion. 

8431.     Seage  &  Seage — Improvements  in  gas  motor  engines. 
9496.      Robson — Improvements  in  gas  or  other  motive  power  engines. 
10051.     Wilkinson Improvements    in    apparatus     for     producing     hydro- 

carburetted  air  for  motive  power  purposes. 

10089.      Beechey Improvements  in  gas  motor  engines. 

10642.     Vogelsang  &  Hille — Improvements  in  valve  gear  of  gas  engines  and 

petroleum  engines. 
10718.      Grob  and  others. — Improved  means  for  effecting  the  ignition  of  vapour 

in  gas  and  petroleum  motors. 
10952.     Griffin — Improvements   in  apparatus  for  regulating  and  governing 

the  admission  of  gas  and  air  into  gas  motor  engines. 
11062.      Lake  (Brayton) — Improvements  in  hydrocarbon  engines. 
11755.      Richardson  &  Norris — Improvements  in  gas  or  vapour  engines. 
11834.     Schiersand An  improved  spring  governor  or  regulator  for  gas  and 

other  engines  and  motors. 
12314.     Holt — An  improvement  in  supply,  exhaust,  and  governing  apparatus 

for  oil  motor  engines. 

12472.     Stuart Improvements  in  compound  hydrocarbon  explosive  engines. 

12678.     Justice  (Baldwin) — Improvements  in  tramcars  and  motors. 

12690.     McGhee   &  Burt — Improvements   in   and    relating    to   gas    motor 

engines. 

12760.  Stallaert.— Improvements  in  motors  adapted  to  be  operated  by  ex- 
plosives. 

13019.     Vermand Improvements  relating  to  gas  engines. 

13051.      Stuart Improvements  in  rotary  motors. 

13352.     Ovens  &  Ovens — Improvements  in  gas  engines. 

13594.     Offen Improvements  in  gas  and  other  explosive  engines. 

14382.     Hall — Improvements  in  igniting  arrangements  for  gas  or  oil  motor 

engines. 

14549.     Roots. — Improvements  in  gas  engines. 

14787.     Robinson. — Improvements  in  gas  or  combustible  vapour  engines. 
14900.     Deboutteville  &  Malandin — Improvements  in  or  connected  with  gas 

engines. 
15309.     Hartley — Improvements  in  hydrocarbon  or  petroleum  engines. 

15525.  Dheyne  and  others — Improvements  in  apparatus  for  use  in  connection 

with  engines  operated  by  gas  generated  from  petroleum  or  other 
liquid  hydrocarbon. 

15526.  Dheyne.— Improvements  in  engines  operated  by  gas  generated  from 

petroleum  or  other  liquid  hydrocarbon. 

15994-  Stuart  &  Binney — Improvements  in  or  connected  with  engines 
operated  by  the  explosion  of  mixtures  of  combustible  vapour,  or  gas 
and  air. 


Appendix  II 


521 


NO. 

16301.     Cruikshank  (White  &  Middleton). — Improvements  in  gas  engines. 
17167.     Pinkney — Improvements  in  and  connected  with  engines  operated  by 

gas  generated  from  petroleum  or  other  liquid  hydrocarbons. 
17299.     Mottershead — Improvements  in  or  connected  with  gas  engines. 
17371.      Higginson — Improvements  in  gas  engines. 
18161.     Sayer — Improvements  in  gaseous  pressure  apparatus  for  producing 

continuous  rotary  or  rectilinear  motion. 
18401.     Griffin. — Improvements    in    apparatus   for   igniting   the   charge  in 

petroleum  and  other  hydrocarbon  motors. 

18645.      Boult  (Sharpneck). — Improvements  in  gas  engine  governors. 
19171.     Kaselowsky. — Improvements  in  ignition  devices  for  gas  motors. 
19513.     Lanchester Improvements  in  the  igniting  and  starting  arrangements 

of  gas  and  hydrocarbon  engines. 

I9559-     Roots Improvements  in  petroleum  or  liquid  hydrocarbon  engines. 

19775.     Lanchester. — An   improved   ignition   device  for  starting  gas  motor 

engines. 

19791.     Lobet Improvements  in  gas  and  other  motive  power  engines. 

19846.     Lanchester — Improvements   in   uniting   and   starting   gear   for  gas 

engines. 
19962.     Griffin. — Improvements  in  petroleum  and  other  liquid  hydrocarbon 

motors. 
20888.     Holt.  —Improvements  in  motor  engines  worked  by  gas,  or  by  oil  or 

other  vapour. 
21165.     Lentz  and  others. — A  single-acting  gas  motor  engine. 

1891. 

103.  Pinkney. — Improvements  in  and  connected  with  engines  operated  by 
"  gas  generated  from  petroleum  or  other  liquid  hydrocarbon. 

no.     Carling.— An  improvement  in  gas  engines  and  other  like  motors. 

191.  Gray.— Improving  engines  actuated  by  the  explosion  of  a  mixture  of 
air  with  the  vapour  of  petroleum  or  other  hydrocarbons,  or  of  tar, 
creosote,  or  other  liquid,  which  when  heated  are  more  or  less  vola- 
tile, and  the  vapour  of  which,  when  mixed  with  air,  forms  an  ex- 
plosive mixture. 

227.     Bickerton Improvements  in  gas  engines. 

297.     Bickerton.— Improvements  in  governors  for  gas  engines. 

383.  Boult  (Berliner  Maschinenbau  Actien  Gesellschaft).—  Improvements 
in  or  relating  to  the  valve  gear  of  gas,  petroleum,  and  other  similar 
engines. 

741.     Adams.— Improvements  in  engines,  motors,  and  pumps. 

816.     MacCallum.— Improvements  in  gas,  petroleum,  and  like  engines. 

834.  Miller.— Improvements  in  petroleum,  oil,  vapour,  gas,  and  other 
explosive  power  engines. 

970.     Williams.-  Improvements  in  gas  motor  and  similar  engines. 


522  The  Gas  Engine 


NO. 


1083.     Robinson. — Improvements  in  gas  or  combustible  vapour  engines. 
1299.      \Villiams — Improvements  in  gas  motor  engines. 

1447.     Weatherhogg. — Improvements  in  gas  and  hydrocarbon  motor  engines. 
1903.     Abel    (Gas-Motoren-Fabrik  Deutz). — Improvements   in  gas   and  oil 

motor  engines. 
2053.      Gray. — Improvements    in  vaporisers   for   generating    petroleum  and 

other  hydrocarbon  vapours  for  use  in  motors  and  engines. 
2815.      Rouzay. — Improvements  in  gas  or  petroleum  engines. 

2976.      Hughes  (Cordenons) Improvements  in  gas  engines. 

3261.     Weiss. — Improvements  in  petroleum  or  oil  motor  engines. 

3350.     Coffey. — An  improved  gas  engine. 

3669.      Rockhill. — An  improved  gas  engine. 

3682.      Wertenbruch. — Improvements  in  or  connected  with  gas  and  other 

hydrocarbon  engines  and  the  pistons  (or  rings)  thereof. 
3830.      Priestman  &  Priestman. — Improvements  in  or  applicable  to  hydro- 

carburetted  air  engines. 
3948.     Trewhella. — Improvements  in  apparatus  for  condensing  and  utilising 

the  residue  of  gases  exploded  to  form  a  vacuum  in  engines  propelled 

by  gas  or  other  explosive  material. 
4004.     Dawes. — A  new  or  improved  apparatus  to  be  used  for  the  starting  of 

gas  or  other  engines. 
4142.     Priestman   &    Priestman. — Improvements   in   hydro-carburetted    air 

engines. 

4222.     Lanchester — Improvements  in  gas  engines. 
4355.     Campbell. — Improvements  in  gas  motor  engines. 
4535-     Griffin.  —  Improvements  in  governing  gas  motor  engines  and  in  con- 
nection therewith. 

4771.     Cooper. — Improvements  in  gas  and  vapour  engines. 
4862.     Lindemann. — Improvements  in  gas  and  petmleum  engines. 
5158.     Vanduzen. — Improvements  in  gas  and  gasoline  engines. 
5250.      Love  &  Priestman  Bros.,    Ltd — Improvements  in  or  applicable  to 

motor  engines  operated  by  the  combustion  of  hydrocarbon  vapour 

or  gas  and  by  the  expansion  of  readily  liquefying  gases. 

5490.     Higginson Improvements  in  gas  engines. 

5663.     Fachris. — An  improved  motive  power  engine,  actuated  by  explosives. 
5747.     Skene. — An  improved  fluid  pressure  regulator. 
6090.     Bickerton — Improvements  in  gas  motor  engines. 
6410.     Day. — Improvements  in  gas  engines. 

6578.      Barclay Improvements  in  and  relating  to  gas  engines. 

6598.      Ridealgh  &  Welford.  —  Improvements  in  gas  or  vapour  engines. 
6717.     Abel  (The  Gas-Motoren-Fabrik  Deutz) — Improvements  in  apparatus 

for  supplying  oil  or  other  liquids  under  a  constant  head  or  pressure. 
6727.     Van  Rennes. — Improvements  in  petroleum  engines. 


Appendix  II  -523 


NO. 


6949.     Key. — Improvements  in  and  relating  to  the  treatment  of  the  discharge 

gases  from  gas  engine  cylinders. 

7047.     Purnell — A  governor  for  gas  and  oil  motor  engines. 
7157.     Altmann.— Improvements  in  governors  for  gas  and  petroleum  motors. 
7313.     Pinkney. — Improvements  in  engines  worked  by  the  explosion  of  gas. 
8032.      Horn  (Vanduzen  &  Vanduzen). — An  improved  gas  engine. 
8069.      Capitaine. — Improvements  in  gas  motors. 
8251.     Barrett  &  Ticehurst. — Improvements  in  motor  engines  actuated  by 

explosions. 

8289.     Hardingham  (Clefand).—  An  improved  rotary  engine. 
8469.     Abel   (Gas-Motoren-Fabrik    Deutz). — Improvements  in  gas  and  oil 

motor  engines. 
8821.     Shillitto  (Grub,   Schultze  &  Niemczik). — Igniting  tubes  for  gas  and 

petro'eum  motors. 
9006.     Boult  (Levasseur) — Improvements  in  gas,  petroleum,  and  carburetted 

air  engines. 

9038.     Southall. — Improvements  in  gas  and  oil  motor  engines. 
9247.      Day.  —  Improvements  in  gas  or  vapour  engines. 
9268.     Bosshardt    (Huntington). — Improvements    in    governors    and   valve 

movements  for  gas  engines. 

9323.     Huelser  (J.   M.   Grob  &  Co.  ).• — A  new  or  improved  gasifying  con- 
trivance for  petroleum  motors. 
9805.     Hawkins. — Improvements  relating  to  vibrating  engines,  applicable  to 

pumps  or  blowers. 

9865.     Dawson. — Improvements  in  gas  engines. 
9931.     Withers  &  Covert.  —  Improvements  in  or  relating  to  vibrating  gas 

engines. 

10298.     Crossley  &  Holt. — Improvements  in  oil  motor  engines. 
10333.      Tiddes  &  Fiddes. — Improvements  in  gas  motor  engines. 

11132.     Irgens Improvements  in  and  relating  to  gas  or  petroleum  engines 

or  motors. 
11138.     Pinkney.— Improvements  in  or  connected  with  engines  worked  by 

gas  generated  from  petroleum  or  other  liquid  hydrocarbon. 
1 1628.     Held.  —A-  new  or  improved  pressure  regulator  for  gas  engines. 

!  1680.     Kasclowsky Improvements  in  gas  and  petroleum  engines. 

1 1851.  Wellington. — An  improved  ignition  tube  for  gas  and  like  engines. 
1 1 86 1.  Lanchester.— Improvements  in  gas  engine  starting  arrangements. 
12330.  Settle.— Improved  means  for  actuating  road  or  tram  cars  and  lake  or 

other  boats. 

12413.     Clerk. — Improvements  in  gas  engines. 
12981.      Menard.  —  Improved  method  and  means  for  firing  the  charges  of  gas 

engines. 
14002.     King  (Connelly) — Improvements  in  gas  motors. 


524 


The  Gas  Engine 


NO. 
I4I33. 

I4I34. 

14209. 
14269. 
14457- 
H5I9. 

14945- 
15078. 
16404. 
I7033- 


I7073- 
17364. 
17724. 

I78I5. 
17955- 


Weyman  &  Drake.  — Improvements  in  governing  and  regulating  the 

supply  of  oil  to  petroleum  or  hydro-carbon  motors. 
Watkinson. — Improvements    in    thermo-dynamic    machines    and    in 

apparatus  and  appliances  connected  therewith. 
Johnson  (Genty).—  Improvements  in  non-return  valves. 
Huelser  (Grob  &  Co.).— Improvements  in  gas  and  petroleum  motors. 
Waller.  —An  improved  apparatus  for  exhausting  gas. 
Abel  (Gas-Motoren-Fabrik  Deutz).  — Improvements  in  igniting  appa- 
ratus for  gas  and  oil  motor  engines. 
Lanchester.— Improvements  in  gas  governors. 

Williams. Improvements  in  gas  and  similar  motor  engines. 

Clerk.  —Improvements  in  gas  engines. 

Shiels Improvements  in  apparatus  for  automatically  regulating  the 

temperature  of  the  water  used  in  cooling  the  cylinders  of  gas  and 
oil  engines. 
Hornsby  &  Edwards.  —Improvements  in  explosion  engines. 

Evers Improvements  in  gas  motor  engines. 

Abel  (Gas-Motoren-Fabrik  Deutz).— Improvements   in  valve   appa- 
ratus for  gas  and  petroleum  motor  engines. 

Evans Improvements  in  gas  engines. 

Pinkney An  improved  metallic  alloy  more  especially  intended  for 

use  for  gas  or  petroleum  engine  igniters,  or  like  articles  subjected 
to  great  heat. 

18020.     Shaw  &  Ashwor i  h.— Improvements  in  gas  engines. 
18276.     Walch  (Dorrington  &  Coates) — Improvements  in  valve  gears  for  gas 
engines. 

18424.     Lee Improvements  in  gas  and  hydrocarbon  motor  engines. 

18621.     Roots  &  Seal Improvements  in  or  connected  with  internal  com- 
bustion engines. 

18640.     Weyman,  Hitchcock  &  Drake Improvements  in  gas  and  oil  hydro- 
carbon engines. 
18715.     Earnshaw  &  Oldfield — Improvements  in  and  connected  with  valves 

of  gas  engines. 
18788.     Clerk — Improvements  in  starting  gear  for  gas  engines. 

19086.     McGhee    &    Burt Improvements   in   and    relating   to   gas   motor 

engines. 

19275.     Roots — Improvements  in  petroleum  or  liquid  hydrocarbon  engines. 
19318.     Barron — Improvements  in  or  appertaining  to  gas  engines. 
19517.     Fielding — An  improved  method  of  starting  gas  engines. 
I9772-     Johnson    (Pieper).  —  Improvements   in   feed    pumps    for    petroleum 

engines. 
I9773«     Johnson   (Pieper) — Improvements  in  the   means  for  regulating  the 

temperature  of  evaporators  of  petroleum  engines. 
19811.     Ridealgh — Improvements  in  gas  and  petroleum  engines. 


UNIVERSITY 


NO. 


Appendix  II  525 


. 

20262.  Robinson.—  Improvements  in  gas  or  combustible  vapour  engines. 
20745.  Robinson.  —Improvements  in  gas  or  combustible  vapour  engines. 
20845.  Perrollaz  —  Improvements  in  lubricators. 

20926.     Knight.—  Improvements  in  engines  worked  by  heavier  hydrocarbons. 
21015.     Weyman,   Hitchcock   &    Drake  —  Improvements   in   oil    or   hydro- 

carbon motors. 
21229.     Weyman,   Hitchcock,  &  Drake.-  Improvements  relating   to  oil  or 

hydrocarbon  motors. 

21406.      Lanchester  —  Improvements  in  gas  engines. 
21496.     Hartley  &  Kerr.  -  Improvements  in  gas  engines. 
21529.     Miller.—  Improvements  in  valve  gear  for  gas  and  other  engines.  ' 
22559.     Leigh  (Forrest   &    Gallice).—  Improvements  in  gas   and   petroleum 

engines. 
22578.     Burt.—  New  or  improved  starting,  stopping,  and  reversing  gear  for 

machinery  driven  by  gas  or  vapour  engines. 
22834.     Seek  —  Improvements  in  gas  and  hydrocarbon  engines. 
22847.     Abel  (The  Gas-Motoren-Fabrik  Deutz).  —  Improvements  in  petroleum 

or  oil  motor  engines. 

1892. 

112.     Richardson.  —  Improvements    in    the    details    of   gas    and    vapour 

engines. 
260.     Edwards  (Petit  &  Blanc).—  Improvements  in  the  means  of  heating 

the  charge  in  gas  and  like  engines. 
520.     Higginson  —  Improvements  in  gas  engines. 
524.     Wilkinson.  —  Improvements  in  the  working  of  gas  engines. 
826.     Rankin  &  Rankin.  —  Improvements  in  petroleum  and  other  hydro- 

carbon motors. 
919.     Noble  &  Brice  —  Improvements  in  lubricators  for  use  in  connection 

with  gas,  oil,  or  other  explosive  engines. 

926.     Simon.  —  Improvements  connected  with  gas  and  like  engines. 
1203.     Southall.  —  Improvements  in  supply  and  discharge  valves  for  gas  or 

oil  motor  engines. 
1246.     Brooks  &  Holt.  —  Improvements  in  or  additions  to  gas  and  vapour 

engines  or  motors. 

1768.     Richardson  &  Norris  —  Improvements  in  gas  engines. 
1814.     Schwarz.  —  An  improvement  in  or  connected  with  gas  engines. 
1879.     Barker  &  Rollason.  —  Improvements  in  and  appertaining  to  gas-bags 

for  gas  engines. 
2181.     Atkinson.  —  Improvements  in  self-starting  apparatus  for  gas  and  other 

internal  combustion  motors. 

2492.     Atkinson.  —  Improvements  in  internal  combustion  engines. 
2495.     Swiderski.  —  An  improved  oil  or  gas  motor. 


526  The  Gas  Engine 


NO. 


2728.  Abel  (Gas-Motoren-Fabrik  Deutz).  —Improvements  in  gas  or  oil  motor 
engines. 

2854.     Leigh  (Spiel).— Improvements  in  liquid  hydrocarbon  engines. 

2862.  Crossley  &  Bradley. — Improvements  in  starting  and  igniting  appa- 
ratus for  gas  or  oil  motor  engines. 

3047.      Instone — An  improved  oil  or  gas  engine. 

3156.      Bradford. — Improvements  in  fluid  pressure  motive  power  engines. 

3165.  Harris. — Improvements  in  tubes  and  apparatus  for  igniting  gas, 
petroleum  and  vapour  engines  by  intermolecular  combustion. 

3203.      Pinkney.  —  Improvements  in  or  connected  with  gas  engines. 

3292.     Czermak,  Bergl,  &  Hutter. — Improvements  in  gas  motor  engines. 

3417.  Humpidge,  Humpidge,  &  Snoxell.  -  Improvements  in  gas  motor 
engines. 

3574.      Robert. — Improvements  in  and  relating  to  gas  engines. 

3909.     Stuart  &  Binney. — Improvements  in  hydrocarbon  engines. 

4078.      Bickerton — Improvements  in  governors  for  gas  engines. 

4189.      Hamilton — Improvements  in  gas  motor  engines. 

4210.      Lanchester Improvements  in  gas  engine  details. 

4347.  Bell  &  Richardson Improvements  in  portable  petroleum  or  liquid 

fuel  engines. 

4352.  Richardson  &  Norris.  —  Improvements  in  and  appertaining  to  combus- 
tion chambers  of  petroleum  or  hydrocarbon  engines. 

4374.  Lanchester Improvements  in  gas  and  petroleum  engines. 

4375.  Richardson  &  Norris.  —  Improvements  in  the  oil-supplying  arrange- 

ments of  petroleum  and  other  hydrocarbon  or  liquid  fuel  engines. 
5445.     Clerk. — Improvements  in  gas  engine  governors  and  valve  gear. 
5740.      Bilbault. — Improvements   in   and    relating    to    gas    and    petroleum 

engines. 
5819.     Michels  (Grob  &  Co. )  — Improvements  in  feeding  devices  for  petroleum 

motors. 
5972.     Bell  &   Richardson.— Improvements  in  semi-portable  petroleum  or 

liquid  fuel  engines. 
6240.     Owen Improvements  in  motors  to  be  operated  by  either  gas  or  liquid 

hydrocarbons. 
6284.     Chatterton. — Method  according  to  which  steam  and  afterwards  gas 

are  used  as  working  fluids  in  the  same  cylinder  for  the  generation 

of  power. 

6655.     Morani. — Improvements  in  gas  motors. 

6828.     Adams. — Improvements  in  rotary  engines,  motors  and  pumps. 
6872.     Shillito  (Swiderski  &  Capitaine) — An  improved  petroleum  motor. 
6952.     Dawson. — Improvements  in  gas  engines. 
7047.     Courtney  (Briienler). — Improvements  in  petroleum  engines. 
7241.     Diesel. —A  process  for  producing  motive  work  from  the  combustion 

of  fuel. 


Appendix  II 


$17 


NO. 

7943.     Sennett  &  Durie — Improvements  in  the  methods  connected  with  the 
production  of  supply  of  steam  and  gases,  and  in  the  utilisation  there- 
of in  engines  for   producing  motive  power,  and  in  the  apparatus 
therefor. 
8128.     Hornsby  &  Edwards.     Improvements  in  engines   actuated    by  the 

explosion  of  combustible  mixtures. 
8401.     Pollock. — Improvements  in  gas  engines. 
8538.     Beugger. — Improvements  in  or  applicable  to  gas  and  hydrocarbon 

engines. 

8678.     Johnson  (Genty). — Improvements   in   furnace  gas  engines  or  aero- 
thermic  motors. 
8733.     Griffin. — Improvements  in  or  in  connection  with  heating  the  igniting 

apparatus  of  petroleum  or  other  liquid  hjdrocarbon  engines. 
9121.     Guillery.— An  improved  rotary  motor,  applicable  also  for  use  as  a 

pump,  ventilator,  or  the  like. 

9161.     Robinson.- — Improvements  in  gas  or  combustible  vapour  engines. 
9439.     Beugger — Improvements  in  petroleum  and  gas  motors. 
9448.     Ogle. —Improvements  in  the  means  for  igniting  the  charges  in  the 

cylinders  of  explosion  engines. 

9674.     Magee — Improvements  in  gas  motor  engines. 
10x591.     Seek.  — Improvements  in  or  connected  with  hydrocarbon  motors. 
10254.     Hamilton. — Improvements   in  valve  operating   and  governing   me- 
chanism of  gas  and  oil  motor  engines. 
10437.     Holt — An  improvement  in  igniting  apparatus  for  gas  and  oil  motor 

engines. 
11141.     Weyman,    Hitchcock,    &    Drake. — Improvements    in    hydrocarbon 

motors  and  in  apparatus  and  appliances  connected  therewith. 
11598.     Thompson  (O'Kelly).  — Improvements  in  or  relating  to  tramcars  and 

in  motors  therefor. 
11708.     Hitchcock   &    Drake. — Improvements   in   oil   engines  and   the  like 

hydrocarbon  motors. 

11928.     Webb. — Improvements  in  gas  engines. 

11936.     Clerk. — Improvements  in  starting  gear  for  gas  and  like  engines. 
11962.     Hornsby,  Edwards  &  Gibbon. — Improvements  in  engines  actuated 

by  the  explosion  or  burning  of  combustible  mixtures. 
12165.     Anderson — Improvements  in  gas  and  oil  motor  engines. 
12183.     Boult  (Charter). — Improvements  in  gas  or  similar  engines. 
13077.     Davy — Improvements  in  gas  engines. 
13088.     Johnson  (Hille).— Improved   mixing  valve   for   petroleum   and    like 

motors. 

13117.  Clerk. — An  improved  method  of  operating,  and  improvements  in, 
gas  or  petroleum  hammers,  gas  pumps,  gas  punching,  riveting 
or  cutting  machines,  in  part  applicable  to  gas  or  petroleum 
engines. 


528  The  Gas  Engine 

NO. 

13204.     Abel  (Gas-Motoren-Fabrik  Deutz) — Improvements   in  gas  and   oil 

motor  engines. 

13859.     Binns. — Improvements  in  gas  engines. 

13939.     Sayer. — A  gas  or  similar  motor  for  stationary  or  locomotive  purposes. 
14317.     Von  Oechelhauser  &  Junkers. — Improvements  in  and  relating  to  gas 

engines. 

14650.      Hogg  &  Forbes. — Improvements  in  hydrocarbon  engines. 
14713.     De  Susini. — Improvements  in  motor  engines  worked  by  either  vapour 

or  other  volatile  fluids  in  combination  with  a  gas  motor  engine  for 

the  utilisation  of  the  waste  heat  thereof. 
15247.     Piers. — Improvements  in  gas  engines. 
15417.     Weyman Improvements  in  and  connected  with  petroleum  and  like 

engines. 
16308.     Maybach. — Improvements  in  the  method  of,  and  the  apparatus  for, 

effecting  a  continuous  circulation  and  cooling  of  liquids  employed 

in  motors  and  compressors. 
J6339-     Griffin. — Improvements   in    liquid    hydrocarbon    and    other    motor 

engines. 
16365.     Briggs  &  Sanborn. — An  improved  lubricating  cup. 

16379.  Briinler. — Petroleum  motor  contrivance  for  pressing  the  petroleum  into 

the  gasificator  by  means  of  the  air  current  introduced  for  the  forma- 
tion of  the  mixture. 

16380.  Briinler — Improvements  in  rotating  petroleum  motors. 

16381.  Briinler Petroleum  motor. 

16382.  Briinler.  —Improvements  in  evaporating  devices  for  cooling  gas  and 

petroleum  motors,  the  cylinders  and  pistons  of  which  are  rotating 

round  a  stationary  crank. 
16413.     Redfern  (La  Societe  Anonyme  des  Moteurs  Thermiques  Gardie). — 

Improvements  in  and  connected  with  gas  engines  or  motors. 
16986.     Whittaker. — Improvements  in  and  connected  with  ignition  tube  for 

gas  engines. 

17277-     Andrew,  Bellamy  &  Garside — Improvements  in  apparatus  for  govern- 
ing the  speed  of  gas,  oil  and  other  similar  motor  engines. 
17391.     Fairfax  (Sohnlein). — Improvements  in  petroleum  motors. 
17427.     Hartley  &  Kerr.— Improvements  in  compound  engines,  and  in  part 

applicable  to  other  gas  engines. 
17632.     Held. — Improvements  in  petroleum  and  like  engines,  applicable  to 

fire  extinguishing  and  other  purposes. 
17732.      Paton.  —  Improvements  in  gas  engines. 
18020.     Southall — Improvements  in  gas  and  oil  motor  engines. 
18109.     Southall. — Improvements  in  gas  and  oil  motor  engines. 
18118.     Gilbert -Russell — Improvements  in  explosion  engines. 
18513.     Cock. — An  improvement  in  gas  engines. 


-  Appendix  II  529- 

Stroch. — Improvements  in  or  connected  with   petroleum  or   other 

hydrocarbon  motors. 

Dowie  &  Handyside.— A  gas  engine  governor  gear. 
Ryland. — Improvements  in  explosion  engines. 
Weyman  &  Ellis. — Improvements  in  utilising  the  heat  taken  up  by 

the  water  employed  for  cooling  the  cylinders1  of  gas,  oil,  or  other 

hydrocarbon  motors. 

Pinkney Improvements  in  gas  engines. 

Andrew  &  Bellamy — Improvements  in  gas,  oil,  and  similar  motor 

engines. 
Andrew  &  Bellamy Improvements  in  gas,  oil,  and  similar  motor 

engines. 

Priestman  &  Priestman. — Improved  means  for  facilitating  the  start- 
ing of  hydro-carburetted  air  engines. 

21475.     Enger. — Improvements  in  gas  engines  or  motors. 
21534.     Altmann — Improvements  in  and  connected  with  spray  apparatus  for 

hydro-carburetted  air  engines. 

21857.  Winckler    (Jastram). — An    improved   arrangement    for   feeding   oil 

engines  with  oil  in  a  duly  regulated  manner. 

21858.  Winckler  (Jastram) An  improved   reversing   gear   for  a   propeller 

worked  by  engine  power,  with  a  reversing  counter-shaft  revolving 
in  an  opposite  direction  to  the  main  shaft. 

21917.  Wetter  (Rademacher). — Process  and  apparatus  for  igniting  the  com- 
bustible charges  or  gas  mixtures  of  gas  and  oil  motors. 

21952.     Diirr. — Improvements  in  hydrocarbon  engines. 

22664.     Stuart  &  Binney — Self-starting  mechanism  for  hydrocarbon  engines, 

22797.  Weyman,  Hitchcock,  &  Drake. — Gear  for  transmitting  and  revers- 
ing the  power  given  off  by  gas  and  oil  motor  engines. 

23323.     Knight — Improvements  in  oil  and  gas  engines. 

23786.  Roots — Improvements  in  or  connected  with  internal  combustion 
engines. 

23800.  Sennett  &  Durie. — Improvements  in  the  methods  and  means  of 
cooling,  heating,  and  lubricating  cylinders,  such  as  those  of  gas 
and  steam  engines,  air  compressors,  and  the  like,  and  of  equalising 
the  motion  of  the  piston  therein. 

24065.  Roots — Improvements  in  gas  engines  and  in  their  application  to 
motor  vehicles. 

1893. 

108.     Fielding. — An  improved  double-cylinder  gas  or  oil  motor  engine. 
153.     Wetter  (Gerson  &   Sachse).— Method  of  varying    the    strength    of 

the  explosion  charge  or  the  ratio  between  the  constituents  of  the 

gas  and  air  mixture  in  gas  engines. 

M  M 


530  The  Gas  Engine 


NO. 


531.     Shuttleworth  and  others.— Improvements  in  furnace  lamps  for  oil 

and  gas  engines. 

608.     Sabatier  and  others. — Improvements  in  gas  and  petroleum  engines. 
735.     Abel  (Gas-Motoren-Fabrik  Deutz). — Improvements  in   gas  and  oil 

motor  engines. 
779.     Shiels Improvements  in  apparatus  for  automatically  regulating  the 

temperature  of  the  water  used  in  cooling  the  cylinders  of  gas  and 

oil  engines. 

1070.     Dawson. — Improvements  in  gas  engines. 

1277.     Burt   &    McGhee Improvements   in  and    relating  to  gas  or    ex- 
plosive vapour  motor  engines. 

21 10.     Dixon An  improvement  or  improvements  in  gas  engines. 

2523,     Mellin  &   Reid. Apparatus   for  deodorising  the  exhaust  of  gas  or 

oil  motor  engines. 

2596.     Lanyon  (Martin) An  improved  hydrocarbon  motor. 

2788.     Evans — Improvements  in  gas  engines. 

2851.     Bellamy. — Improvements  in  gas  and  similar  motor  engines. 

2912.     Weyman Improvements  in  or  connected  with  lamps  and  vaporisers 

for  oil  engines. 

3332.     Hartley  &  Kerr Improvements  in  gas  engines. 

3401.     Davy. — Improvements  in  gas  engines  or  other  internal  combustion 

engines. 

3971.     Hartley  &  Kerr Improvements  in  compound  gas  and  like  engines. 

4327.     Heys  (Langensiepen) — A  new  or  improved  admission  valve  for  gas 

or  o  1  engines 

4564.     Bellamy. — Improvements  in  gas  and  similar  motor  engines. 
4696.     Davy. — Improvements  in  gas  and  other  internal  combustion  engines. 
5005.      Rollason — A  device  for  preventing  the  bursting  of  gas  engine  and 

other   water -jacketed   cylinders  or    pipes  by  the  freezing  of  the 

water. 

5256.     Lake  (Backeljau) — Improvements  in  explosive  gas  actuated  pump. 
5456.     Trewhella — Corrugated  cylinders  for  internal  combustion  engines. 

6093.     Bellamy Improvements  in  gas  and  similar  motor  engines. 

6204.     Sayer. — Improvements   in  explosive  and    pressure  elastic  and  non- 
elastic  turbine  engines. 

6453.     Okes Improvements  in  internal  combustion  engines. 

6534.     Berk. — Improvements  in  or  connected  with  gas  and  oil  engines. 
7023.     Owen. — Improvements    in    or   in    connection    with   self-generating 

vapour  burners,   or  apparatus  for  vaporising  liquid  hydrocarbons 

for  heating,  lighting,  or  other  purposes. 

7064.     Bellamy — Improvements  in  gas  and  similar  motor  engines. 
7292.     Walker. — Exhaust  scrubber  for  petroleum  and  other  motors  having 

offensive  or  injurious  exhaust. 
7426.     Dawson,  —  Improvements  in  gas  engines. 


Appendix  II 


531 


NO. 

7433.     List   and   others. — Improvements  in  and  connected  with  what  are 

-commonly  known  as  petroleum  or  oil  engines. 
7466.     Burt. — Improvements  in  variable  speed  and  reversing  mechanism  for 

gas  or  vapour  or  other  motors. 

8095.  Morcom. — Improvements  in  working  motive  power  engines,  and  in 
apparatus  actuated  by  combustible  gases  to  be  employed  for  that 
purpose,  and  for  other  purposes. 

8158.  Lindahl. — Improvements  in  or  relating  to  admission  valves  for  petro- 
leum or  similar  motors. 

8409.     Wilkinson Improvements   in    and    relating  to  gas,  oil,   and   like 

power  motors. 

8639.     Drake. — Improvements  in  hydrocarbon  engines. 
8864.     Robinson,  A.  E.  &  II. — Improvements  in  oil  or  gas  engines. 
8967.     Crouan — Improvements  in  gas  and  other  motive  power  engines. 
9181.     Abel  (Gas -Motor en -Fabrik  Deutz). — Improvements  in  gas  and    oil 

motor  engines. 

9216.     Okes. — Improvements  in  internal  combustion  engines. 
9549.     Bruckert   &   Delattre. — Improvements   in   rotary  motors  applicable 

also  as  pumps. 

9618.     Roots. — Improvements  in  internal  combustion  engines. 
10240.     Gessner. — Improvements  in  steam  and  other  engines  and  pumps. 
10274.     Abel  (Gas-Mgtoren-Fabrik  Deutz). — Improvements  in  valve  gear  for 

gas  and  petroleum  motor  engines. 

10310.     Hartley  &  Kerr. — Improvements  in  gas  and  like  engines. 
10801.     Peebles. — Improvements  in  or  connected  with  gas  or  vapour  motors. 
12330.     Grove. — Improvements  in  heating  lamps  applicable  to  hydrocarbon 
engines,  and  apparatus  therefor. 

12388.     List  and  others Improvements  in  what  are  commonly  known  as 

petroleum  or  oil  engines. 

12427.     Dougill. — Improvements  in  gas  and  explosive  vapour  motors. 
12600.     Drysdale.  —  Improvements   in   valves    and   atomising   apparatus   for 

hydrocarbon  engines. 
12732.     Morgan. — Improvements   in   combustible   vapour    engines,    and    in 

their  accessories. 
12843.     Priestman,  W.  D.  &  S. — Improvements  in  or  applicable  to  internal 

combustion  engines. 

12917.     Pul.len. — An  improved  oil,  spirit,  gas,  or  steam  motor. 
13282.     Furneaux  &  Butler. — Improvements  in  starting  apparatus  for  gas  and 

other  motors. 
13518.     Fiddes,  A.  &  F.  A. — Improvements  in  gas  and  vapour  motor  engines 

and  the  like. 

14212.  Smethurst  and  others — Improvements  in  methods  of,  and  apparatus 
for,  applying  combustible  mixtures  of  air  and  gas  or  inflammable 
vapour  to  driving  motive  power  engines. 

MM  2 


;S32  The  Gas  Engine 

NO. 

14454.     Bickerton. — Improvements  in  starting  apparatus  for  gas  engines. 
14546.      Boult  (The  C.D.M.  Niel). — Improvements  in  or  relating  to  automatic 

starting  gear  for  motors  operated  by  explosion. 
14558.     Hornsby  &  Edwards. — Improvements    in  engines  operated    by  the 

explosion  of  mixtures  of  combustible  vapour  or  gas  and  air. 
14572.     Thompson  (Diirr).  — New  or  improved  vaporisers  for  petroleum  motors. 
14891.     Boult  (La  S.  F.  des  M.  C.). — Improvements  in  or  relating  to  petro- 
leum, gas,  or  oil  engines. 

15199.      Campbell Improvements  in  oil  and  gas  motor  engines. 

15359.      Bellamy. — Improvements  in  travelling  cranes. 

15405.     Fryer. — Improvements  in  valve  gear  for  the  '  Clerk  '  and  like  type  of 

gas  engine  in  which  a  separate  air  and  gas  pump  is  employed. 
15900.     Boult  (Brauer  &  Windnitz). — Improvements  in  rotary  engines  and 

pumps. 
15947.     Simms. — Improvements  in  or  connected  with  whistles  or  the  like  for 

explosion  engines. 
16072.     May  bach. — Improvements  in  the  method  of  producing  the  explosive 

mixture  in  hydrocarbon  engines. 
16079.     Tipping. — Improvements   in    rotary  pumps,    blowers,   and   engines, 

also  applicable  for  measuring  fluids. 
16290.     Qurin. — Adjustable  cam. 

16410.     Spiel  &  Spiel. — Improvements  in  hydrocarbon*  engines. 
16575.     Drake. — Improvements   in  the  vaporisers  and  ignition  tubes  of  oil 

engines. 

16751.  Briinler. — Device  in  gas  or  petroleum  engines  with  slow  combustion 

for  insuring  the  maintenance  of  the  combustion. 

16752.  Briinler — Process  for  insuring  the  commencement  of  the  ignition  in 

gas  and  petroleum  engines. 

16900.     Crossley  &  Atkinson.— Improvements  in  internal  combustion  engines. 
16985.     Maybach.— Improvements  in  the  method  of  igniting  the  explosive 

mixture  of  hydrocarbons. 
17784.     Shuttleworth    and    others.  —Improvements   in   and    for    connecting 

together  lamps  and  vaporisers. 
18152      Sherrin  &  Garner. — Improvements  in  cylinders  and  pistons  for  gas 

and  other  heat  engines. 

20007.     Ryland. — Improvements  in  explosive  engines. 
20808.     Priestman,  W.  D.  &  S. — Improved  means  applicable  for  use  in  mixing 

liquids  with  gases  in  the  manufacture  of  vapour. 
21 1 20.     Hamilton. — Improvements  in  gas  motor  engines. 
21775.     Briinler. — Process  for  obtaining  a  compression  in  gas  and  petroleum 

engines  with  slow  combustion. 

21908.     Barclay. — Improvements  in  and  relating  to  sight-feed  lubricators. 
22181.     Roots. — Improvements  in  internal  combustion  engines. 
22753.     Pinkney.— -Improvements  in  internal  combustion  engines. 


Appendix  II 


533 


NO. 

23°75-  Crossley  &  Atkinson. — Improvements  in  gas  or  internal  combustion 

engines. 

23175.  Stoke — Outlet  valve  motion  for  gas  and  petroleum  engines. 

23379.  Wattles. — Improvements  in  gas  engines. 

23571.  Roots Improvements  in  internal  combustion  engines. 

23735.  Switz  and  others. — Improvements  in  gas  and  other  explosive  engines. 

24258.  Durand. — Improvements  in.  or  relating  to  explosion  engines. 

24384.  Hamilton — Improvements  in  gas  motor  engines. 

24584.  Crossley  &  Hulley. — Improvements  in  internal  combustion  oil  engines. 

24612.  Sitton. — Improvements  in  oil  engines. 

24666.  Campbell — Improvements  in  gas  motor  engines. 


534 


NAME    INDEX 


TO 


GAS    AND    OIL   ENGINE    PATENTS 


ABE 

ABEL,  C.  D.  (Beissel),  1882 — 3435 
(Daimler),  1879 — 3245  ;   1880 — 

(Langen  &  Otto),  1866 — 434; 

1867 — 2245 

(Daimler)  1874—414,  605 ; 

1875—71 

(Gas-Motoren-Fabrik  Deutz), 

1885—11933;  1886—5804;  1887— 
847,  1189,  11503,  12187,  17188, 
17896  ;  1888—688,  3020,  3095, 
5724,  9602,  14349  ;  1889—5616, 
18746,  20892  ;  1891 — 1903,  6717, 
8469,  14519,  I7724.  22847;  1892— 
2728,  13204  ;  1893—735,  9181, 
10274 

(Otto),  1875—3615;  1876— 

2081;  1878 — 1770;  1881 — 60; 
1883 — 1677 

(Spiel)  1881—4244 

Adam,  1887 — 1266 

Adams,  1891 — 741  ;  1892 — 6828 

Aeugenheyster,  1888 — 13414 

Ainsworth,  1884—8960 

Alexander,  E.  P. ,  1875 — 4342  I  *&79 — 
39°5 

Allcock,  1881—565 

Allison  (McNett),  1889 — 12045 

Altmann,  1888 — 8317  ;  1891 — 7157  ; 
1892—21534 

Anderson  J. ,  1854 — 191 ;  1859 — 2767  ; 
1866—3363 ;  1871 — 2326  ;  1882 — 
1754  ;  1887 — 15010 

Anderson,  1888 — 14248,  17413  ;  1892 
— 12165 

Andrew,    1883 — 1010,     3066,    4291 ; 


BAR 

1884 — 13221  ;    1885—5561  ;    1892 — 

17227,  20802,  20803 
Angele,   1879—3905 
Antisell  &  Bruce,  1875 — -2016 
Arbos,  J.,  1862 — 3108 
Archat,  1887—9111 
Archibald,  C.  D.,  1858—996 
Aria,  1888—9342 
Ashbury  &  others,  1882—5188 
Asher,  1885 — 1424 
Ash  worth,  1891 — 18020 
Atkinson,    1879—3213;    1881—4086 ; 

1882—4378,      4388  ;      1884—3039, 

16404;    1885—2712,    3785,    15243; 

1886—3522  ;  1887—11911  ;  1889— 

20482  ;  1892 — 2181,    2492  ;  1893— 

16900,  23075 
Aylesbury,  1880 — 3512 


BABBITT,  1867—3690 

Babacci,  G.  B.,  1868—1393 

Babcock,  1886 — 478 

Backeljau,  1884 — 11361  ;    1893—5256 

Bainford,  1887 — 2236 

Baldwin,  1882 — 4886  ;  1890 — 12678 

Balestrins,  H.,  1855 — ion 

Bauer  and  anr. ,  1881 — 1074 

Banki,  1889—6296 

Barber,  J.,  1791—1833 

Barclay,  1891 — 6578;  1893—21908 

Barker,   1887 — 14027;    1888—11242; 

1892 — 1879 

Barnett,  W.,  1838—7615 
Barnett,  1889 — 18847 
Baron,  1879 — 2 


Name  Index 


535 


BAR 


BUT 


Barrett,  1891—8251 

Barren,  1878 — 1170  ;  1891 — 19318 

Barsanti  £  Matteucci,  1854 — 1072 

-  1857—1655  ;  1861—3270 
Baxter  (Hoist),  1890 — 5005 
Beck,  1881-5534 
Bechfeld,  1887—14952 
Beechy,     1880 — 1653,    4270  ;    1881 — 

2961 ;    1882 — 1318  ;     1885 — 3199  ; 

1887—4160,  8818  ;  1890 — 10089 
Beissel,  1882—3435 
Bell,  1892—4347,  5972 
Bellamy,  1892—17277,  20802,  20803; 

1893—4564,  6093,  7064,  15199 
Bellini  &  Carobbi,  1874 — 9°^ 
Benger,  1888—5204 
Benier, '    1881 — 1541,     4589;    1882 — 

1868  ;   1884—16131  ;   1887—1262 
Bennett  and  anr. ,  1882 — 6136  ;  1887 — 

11567 
Benson  (Rider),  1879 — 2191  ;  1880— 

4250 

Benz&Co.,  1884—9949,  1886—5789 
Bergl,  1892 — 3292 
Berk,  1893 — 6534 
Bernadi,  1886—5665 
Bernstein,  1884 — 1457 
Bessemer,  H.,  1869 — 1435 
Beugger,  1892—8538,  9439 
Bickerton,   1880—4633  ;  1881—1363  ; 

1885—5519  ;  1885—15845  ;    1887— 

17896 ;  1891 — 227,  297,  6090 

—  and     anr.,     1882 — 2345  ;     1892 — 
4078  ;  1893—14454 

Bilbault,  1892 — 5740 

Binney,    1886 — 15319;    1888 — 10667; 

14076  ;  1889—14868  ;    1890-7146  ; 

15994  ;  1892 — 3909,  22664 
Bisschop,  1872 — 1594  ;   1882 — 579 
Black,  1885—14574 
Blanchard,  F.  B.,  1855 — 339 
Bland,  1892 — 260 
Blessing,  1888 — 1381 
Blyth,  1887—516 
Bobrownicki,  1866 — 181 
Bolt,  1886—11576 
Bolton,  R.  L.,  1853—515 
Bosshardt  (Huntington),  1891 — 9268 
Boult   (Larrivel   &     Aeugenheyster), 

1888 — 13414 

—  (Berliner     Maschinenbau    Actien 
Gesellschaft),  1891—383 

—  (Brauer  &  Windisch),  1893—15900 

—  (Capitaine),    1888—15840,    15841, 
15845,  15846 

—  (Charter),  1892 — 12183 

—  (Compagnie  des    Moteurs   Niel), 
1893—14546 


Boult  (La  Socie"te~  des  Moteurs  Cre- 
bessac),  1893—14891 

—  (Rotten),  1889—17024 

—  (Sharpneck),  1890 — 18645 

—  (Levasseur),  1891 — 9006 
Boulton,  M.  P.  W.,  1864—1099, 

1291  (1864),  1636,  3044 ;  1865 — 
501,  827,  1915,  1992;  1866—738; 
!  868— 1988  ;  1876 — 2288,  3620, 
3767  ;  1877 — 766  ;  1878—2278, 
2525,  2609,  2707;  1878—495; 
1881—1202,  1389,  3367 ;  1886— 

2653 

Bouneville,  H.  A.,  1867 — 1575 
Bourne,  J.,  1868—1878,  3594  ;  1869- 

3705  ;  1870—1859 
Bousfield  &  another,  1833—388 
Bower  &  Hollingshead,  1868—2808 
Boys,  1886—10332 
Bradford,  1892 — 3156 
Bradley,  1892—2862 
Braham  &  another,  1882 — 2751 
Brandon,  A.  H.,  1869—3178 
Brauer,  1893 — 15900 
Vrayton,  1874 — 2209  ;  1890—11062 
Bre^ttmayer,     1880 — 3140  ;       1887 — 

16257 

Brice,  1892 — 919 
Briggs,  1892—16365 
Brightmore,  1888 — 4057 
Brinn,  Q.  L. ,  1875 — 3274 
Brine,  1884 — 12312  ;  1886 — 942 
Brinns,  1890—4362  ;  1892 — 13859 
Briscall,  1883 — 5020 
Brooks,  1892 — 1246 
Brooman,  R.  A.,  1863 — 2098 
Browett,    1884—14341  ;    1887 — 2520, 

11345;  1888—7547,  16057;  1889— 

18847 
Brown,      S.,      1825 — 5150;       1826— 

5350  ;        1846 — 11072  ;         1882 — 

1874 

Bruce  &  Antisell,  1875—2016 
Briickert,  1893 — 9549 
Briinler,     1886—2140;      1892 — 7047, 

16379,  16380,  16381,16382;  1893— 

16751,  16752,  21175 
Brutton,  1889—6161 
Brydges,   1881 — 3330 
Bull.     1883 — 5113  ;        1887 — 10202  ; 

1889 — 10634 
Bullock,  1883 — 5085 
Burgh, 1885 — 15194 
Burt,      1887—11678  ;       1888—3427 ; 

i8qo — 12690  ;  1891 — 19086,  22578, 

1893—1277,  7466 
Buss,  1875 — 1933 
Butcher,  1879—2618,   4377 ;    1880— 


536 


The  Gas  Engine 


BUT 


DAW 


474;      1881 — 3786;       1883—1835; 

1884—5641 
Butler,      1887—15598 ;     1888—1780, 

1781  ;  1890 — 6990 
—  &     others,     1889—9203 ;     1893 — 

13282 
Butterworth,        E. ,         1874 — 1652  ; 

1884—11086  ;      1886 — 207,      7936, 

12134 

Buttress,  1885 — 1424 
B)erley  &  Collins,  1838 — 7871 


CAMPBELL,  1883 — 5951 ;  1885—6990  ; 
'   1888 — 10748  ;  1891—4355  j  1893— 

15199,  24666 
Capell,  1883—911 
Capitaine,        1888 — 15840,         15841, 

15845,  15846  ;  1891—8069     1892 — 

6872 

—  (Benz  &  Co.),  1884—9949 

—  £    Briinler,      1885 — 7500,      7581, 
1886 — 2140 

Carling,  1891 — no 

Carrobbi  &  Bellini,  1874 — 961 

Carosis,  A  ,  18^3 — 1671 

Casper  (Tavernier),  1887 — 4757  ;  1888 

—5628 

-  1889—7069;   1890—1586 
Casson,  1878 — 3774 
Cattrall,  1885 — 11555 
Charon,  1888 — 12399 
Charter,  1887 — 1168  ;  12749  !   l892 — 

12183 

Chatterton,  1892 — 6284 
Chemin,  1888—9342 
Clark,  A.  M.  (Hurcourt),  1868 — 354 

(Lesnard)  1869—1748 

(Fell),  1879—1996 

(Kabath),  1883—999 

(Laurent),  1882 — 6136 

Clark,  W.,  1858—969 

—  (Merlanchon),  1863 — 1449 

—  (Bobrownicki),  1866—181 
Clark  ^  Economic  Motor  Co.),  1883 — 

4260,  1885 — 11294  ;  1885 — 12483 

(Hopkins),  1884 — 11837 

Clayton,     1878—2037;    1879 — 3140; 

1880—4075  ;    1882—2202 ;    1884— 

2854 
Clerk,    D.,   1877 — 252;    1878—3045; 

1879—2424  ;    1881—1089  ;    1882— 

4948  ;     1883 — 4046  ;     1886-12912  ; 

1889—8805;    1891 — 12413,    16404, 

18788  ;  1892—5445,  11936,  13117 
Clerk  and  ors. ,  1881 — 3536 
Cliff  and  anr.,  1883—638 
Coates,  1890  —6910  ;  1891 — 18276 


Cobham  and  anr. ,  1884—3495 
Cock,  1892 — 18513 
Coffey,  1891 — 3350 
Cohade,  H.  F.  1860—1585 
Collins  and  Pyerley,  1838—7871 
Colton  (Hartig),  1885—9801 
Connelly,  1890 — 5621  ;  1891 — 14002 
Cooke,  1883 — 326 
Cooper,  1891 — 4771 
Cordenons,  1889—6748 
Cormack,  W. ,  1846 — 11245 
Courtney  (Brunler),  1892-  7047 
Cousins  and  anr.,  1879 — 4101 
Covert,    1889 — 12472,  20249  ;  1891 — 

993 1 

Crebassac,  1893 — 14891 
Crist,  1889—20249 
Cropper  1878—3444 
Crossley,    1880 — 4297  ;     1881 — 2227  ; 

1882—4489  ;     1883 — 1722,      3079  ; 

1884-4777,     11578  ;    1885—8134  ; 

1886—11285;  1887 — 5833;    1888 — 

1705-  3756-  4624 
Crossley,  F.  W.,  1874 — 3205 
and  W.  J.,  1875 — 3221  ;  1877 — 

2177 

—  1876 — 132 

—  and  anr.,  1878 — 5113  ;  1879 — I9I2» 
4499  ;  1880—3411!  1881—370,  3450, 
5469  ;     1882—1754,    3449 ;     1884— 
3537,  15311  ;  1887 — 15010;  1888 — 
14248,  17413  ;  1891 — 10298;  1892 — 
2862  ;  1893 — 16900,  23075,  24584 

Crouan,  1893 — 8967 

Crowe     and     others,      1883—2706 ; 

1889—7594 

Cruikshank  (White),  1890 — 16301 
Csouka,  1889 — 6296 
Cunynghame,  1886—10332 
Czerniac,  1892 — 3292 


DAIMLER,  1874 — 4*4'  605  ;  ^7^ — 71 ; 

1879—3245  ;    1883—5784  ;     "1885— 

4315,  10786  ;  1885 — 13163 ;  1886 — 

14034  ;  1889 — 10007 
Dalton  and  another,  1879 — 34^7 
Daly,  1889—18847 
Davey,  1882—2527,  37:7 
Davies,  1883 — 781 
Davy,      1884—42264;      1886—3473; 

1887 — 7677,   13916,  15658  ;  1892— 

13077;  1893—3401,  4696 
Dawes,  1891 — 4004 
Dawson,    1885 — 792°  <     l886 — 4460; 

1887 — 6501  ;    1890 — 6407  ;    1891  — 

9865  ;  -1^92— 6952  ;       1893—1070, 

7426 


Name  Index 


537 


DAY 


GEI 


Day,  1891  —  6410  ;  9247 

Deacon,  1886  —  3010 

Deboutteville    &    Malandin,     1884  — 

3986,    6652,    15248  ;  1885—15710  ; 

1886—11  ;  1888.—  2805,  8300,  9249  ; 

1890  —  14900 
Dellatre,  1893  —  9549 
Dewhurst,  1884  —  5412 
Dheyne,      and     others,     1890  —  5933, 


Dickson,  J.  F.  ,  1875  —  744 

Diederichs,  1889  —  14926 

Diesel,  1892—7241 

Dinsmore,  1885  —  13309 

Dixon,  1893  —  2110 

Donald,  1879  —  54° 

Dorrington,  1890  —  6910  ;  1891  —  18276 

Dougill,     1  88  1  —  2122  ;     1883  —  3097  ; 

1884—12318  ;  1887—10360  ;  1888— 

9587;   1893—12427 
Douglas,  J.  C,  1835—6875;  1884— 

11750 

Dowie,  1892  —  20088 
Drake    and    another,     1881  —  4407  ; 

1882  —  1717  ;     1891  —  18640,    21015, 

21229;  1892  —  11141,  11708,22797; 

1893-8639 

Drake,  1893—16675  (see  ante] 
Drysdale,  1893—12600 
Ducretet,  1887  —  9717 
Duerr,  1889  —  20161 
Dufrene  and  others,  1882  —  1868 
Durand,  1888—6088  ;   1893—24258 
Duric,  1892  —  7943,  23800 
Durr,  1892—21952  ;  1893  —  I4572 
Dutton  (Spiel),  1883  —  4°°8 
Dyson,  1882—5527 


EARNSHAW.  1891 — 18715 
Economic  Motor  Co.,  1883 — 4260 
Edington,  J.  C. ,  1854—549 
Edison,  1883 — 1019 
Edmonds  (Fra^ois),  1879 — 482° 
Edwards,     1880—760  ;    1881 — 1765  ; 

1891 — 17073;    1892 — 8128,    11962; 

1893—14558 

Edwards  (Petit  &  Bland),  1892—260 
Ellerbeck  &  Syers,  1875—4326 
Ellis,  1892 — 20660 
Ellis  and  another,  1881 — 1409 
Embleton,  1887 — 11717 
Emery,  1867 — 571 
Emmet,  1882—397 
Emmet  and  another,  1879 — 4IQI 
Enger,  1892 — 21475 
PIteve    and      another,    i83i — 3113'  ; 

1884-2135 


Evans,  1891—17815  ;  1893—2788 

Evers,  1891 — 17364 

Ewins  and  another,  1881 — 1388 


FABER,  1887 — 7350 

Fachris,  1891 — 5663 

Fairfax,  1884—13573 

—  (Sohnlein),  1892 — 17391 

Fairweather  (Babcock),  1886 — 478 

Fiddes,     1880 — 5219;    1891 — 10333; 

1893— i35l8 
Fielding,       1881 — 532  ;      1882 — 994  ; 

1883—3070 ;    1884—2933  ;     1886— 

3402,     9563  ;    1890 — 6912 ;    1891 — 

19517  ;  1893 — 108 
Firth,  W.,  1870 — 2554 
Fogarty,  1873—3848 
Forbes,  1892 — 14650 
Ford,     S.,    1874 — 486;    1881 — 2280; 

1889 — 20115 
Forest,  1883 — 19 
Forrest,  1891 — 22559 
Foster,  1872 — 387 
Foulis,     1878 — 4630,     4843  ;    1879 — 

2073.     47551    1880—2422,      5090; 

1881—180;  1883—3280 
Francois,  1878 — 2474  ;  1879-4820 
Franklin  &  Dubois,  1869 — 1375 
Frederking,  1889 — 20166 
Friend,  1888—11614 
Fryer,  1893—15405 
Furneaux, 1893 — 13282 


GALLICE,  1891 — 22559 

Gait,  1887—1168,  12749 

Gambardella,  P.,  1859 — 1345 

Gardie,  1883 — 3383  ;  1886 — 6161  ; 
1888—2649;  1892—16413 

Garner,  1893—18152 

Garrett,  1885—4684 

Garside,  1892 — 17277 

Gas-Motoren-Fabrik  Deutz,  The, 
1885—11933  ;  1887 — 847,  1189, 
11503,  12187,  17108,  17896  ;  1888 — 
688,  3020,  3095,  5724,  9602,  14349  ; 
1889 — 5616,  18746,  20892  ;  1890 — 
1943,  4164;  1891—1903,  6717, 
8469,  14519,  17724-  22847  ;  1892— 
2728  ;  1893—735,  9181,  10274 

Case,  1888—3964,  6036 

Gavillet,  1887—2194 

Gedge,  W.  E.,  1865—2600  ;  1867— 

3237 

-    (Marti    &    Quaglis),    1882— 
5042 
Geisenberger,  1880—533 


538 


The  Gas  Engine 


GEN 


HOR 


Genty,  1891 — 14209;  1892—8678 

George,  R.,  1866 — 3125 

Gessner,  1893  —  10240 

Gibbon,  1892 — 11962 

Gilbert-Russell,  1892—18118 

Gill,  J.,  1868—2264 

Gillespie  and  another,  1884 — 3495 

1886—6612 

Gillott,  1885—11558 

Gilman  &  Sowerby,  1825 — 5150 

Girardet,  1889—16393 

Glaser,  1879 — 3732  ;  1882 — 2008 

Glazebrook,  J.,  1797 — 2164 

1801—2504 

Goodrich,  1872 — 3641 
Gottheil,  R. ,  1874  —  25 
Graddon,  1879 — 1161,  4483  ;  1880 — 

5479  ;  1881—799 

Gray,  1885 — 15194;  1891 — 191,  2053 
Green,  1884— 8489;   1889 — 16202 
Griffin,      1881-5483;     1883—4080; 

1884 — 3758,  11576,  14311 ;    1886  — 

15764  ;  1887—3934,  10460  ;  18^,0— 

6217 

—  1890—10952,   19962  ;    1891—4535, 
1892 — 8733  ;  1892 — 16339 

Griffith,  1884 — 12201 

Grob,     1890 — 2919,     10718  ;    1891 — 

8821,  9323,  14269 
Groth,  1881 — 1382 

—  (Daimler),      1883—5784,      1884— 
9112  ;  1885 — 13163 

Grove,  1893 — 12330 
Guillery,  1892 — 9121 
Guthrie,  1882—2337 ;  1884—9001, 

10483 
Gwynne  and  another,  1881 — 1409 


HADDAN  (Schiltz),  1883—4455 

—    —    (Gavillet     &     Martaresche), 

1887 — 2194 

(Archat),  1887 — 9111 

Haedick,  1889—17008 

Hahn,  1887 — 10176 

Haigh     and    another,     1880 — 1969 ; 

1881 — 811  ;      1882—614  ;      1883  — 

2517 

Hale,  1883—2192 
Haley  &   Mills,   1875 — 265  ;    1877 — 

3024 

Hall,  1890—14382 
Hallewell,    R.,     1875—2826;    1876— 

4987,      4988;    1877—819;    1878— 

1798,  5092  ;  1879—1450 
Hamilton,  1888—3546  ;  1889 — 16434  ; 

1890—6015  ;    1892 — 4189,     10254  ; 

1893—21120,  24384 


Handford,  1883—1019 

Handyside     and      another,      1881 — 

3536  ;  1892 — 20088 
Hannan,  1886 — 2993 
Hannoversche  Maschinenbau  Actien 

Gesellschaft,  The,  1878—1997 
Hardaker,  1880 — 2290 
Hardingham  (Cleland),  1891  —  8289 
Hargreaves,        1887 — 5485  ;      1888 — 

10980,        12361,      18761  ;     1889— 

14789 

Harris,  1892 — 3165 
Hartig,  1885 — 9801 
Hartley,  1889 — 2760  ;  1890 — 1=1309  ; 

1891—21496  ;   1892—17427  ;  1893 — 

3332..  3971-  10310 
Haseltine,  G.  (Leggo),  1871 — 2254 

(Goodrich),  1872 — 3641 

(Brayton),  i8;4 — 2209 

Haseltine,  S. ,  1852 — 14086 

Hawkins,  1891 — 9805 

Hazard,  £.,  1826 — 5402 

Hearson,  1886 — 15955  ;  1887 — 12592  ; 

1888 — 14401 
Hees,  1879—3732 
Held,  1891 — 11628  ;  1892 — 17632 
Henderson    (Lteve  &   Braam),    1884 

—2135 

Henniges,  1880 — 4159 
Hetherington,  W.  I.,  1869 — 3585 
Heurtebise,  1866—3448 
Heys  (Langensiepen),  1893 — 4327 
Higginson,       1890 — 17371  ;       1891  — 

5490;   1892—520 
Hill,      1884—5007,      12603  I    1885— 

7104 

Hille,  1890—10642 
Hilton,  1878—10 
Hitchcock,  1891 — 18640,21015,  21229  ; 

1892—11141,  117708,  22797 
Hock,  J.,  1874—493 
Hoelljes,  1889—12447 
Hogg,  1892—14650 
Holder,  1883—3336,  5265 
Hollingshed      &      Bower,       1868  — 

2808 

Holmes,  J.  E. ,  1864—1288 
Holt,  1884 — 3893,  8211,   15312;  1885 

— 3747  ;  1890 — 12314,  20888  ;  1892 

—1246,  10437 
Holt  &  Crossley,   1879—1912,  4499 ; 

1880  —  3411^     1881—370,      3450, 

5469  ;     1882-3449  ;    1884  —  3537, 

15311  ;  1888—14248  ;  1891 — 10298 
Hopkins  and  another,    1879 — 3561  ; 

.1883—2492,  5406  ;  1884 — 11837 
Horn  (Vandusen),  1891 — 8032 
Home,  1880 — 5024 


Name  Index 


539 


HOR 


Hornsby,    1891 — 17073  ;  1892 — 8128, 

11962  ;  1893 — 14558 
Hosack,  1887—888 
Howard  and  another,  1883 — 388 
Howden,  1889—9685 
Huesler  (Grob),  1891 — 9323 
Hughes,  E.  T.,  1872—3481 

(Cordenons),  1891 — 2976 

Hugon,  P.,  1860 — 615,  2902  ;  1863 — 

653,  65986 
Hulley,  1893—24584 
Humes,     1885—8411;    1886—1464, 

5597,  11269,  i3229  I  1888—5632 
Humpidge,  1892 — 3417 
Hunt,  1889—9685 
Hunter,  J.  M.,  1868 — 2680 
Huntington,     1889—14592  ;    1891  — 

9268 

Hurcourt,  1868—354 
Hurd,  1879—2193 
Hutchinson,        1880 — 5471;    1882  — 

2329  ;  1886 — 4785,  12086,  14269 
Huiter,  1892 — 3292 
Hydes  &  Bennett,  1869 — 3087 


iMRAYj,  1873—1946;  1888—1336 

(Glaser),  1889 — 8778 

(Schweiser),  1883—836 

(Weilbach),  1889—3887 

Instone,  1892 — 3047 
Ireland,  1885 — 1478 
Irgens,  1891 — 11138 


JANIOT,  1889 — 17295 
lastram,  1892 — 21857,  21858 

enkin,  F.,  1874 — 2441 

enner,  1880—3607 
Jensen,  P.,  1872 — 1423 

—  (Weilbach),  1888—15858 
Johns,  1884—5302,  5303 
Johnson,  J.,  1841 — 8841 

Johnson,    J.    H.,    1860—335;  1861— 
107;  1874—2795 

(Bisschop),  1882 — 579 

(Franfois),  1878 — 2474 

(La       Socie'te'      des      Moteurs 

Labrigot),  1877—3159 

(Wertheim),  1876 — 3444 

Johnson,  1879—2732,  1880—1131 

—  (Deboutteville      and     Malandin), 
1884—3986  ;  6652,    15248  :  1885— 
15710  ;  1886 — ii  ;   1888 — 2805 

—  (Genty),  1891 — 14209;  1892—8678 

—  (Hille),  1892—13088 

—  (La  Socie'te"  des  Tissages  et  Ateliers 


LAK 

de  Construction  Diederichs),  1887 

—  (La  Socie'te'  Salomon),  1888—2804 

—  (Lenoir),  1883—5315  ;   1885—610 

—  (Pieper),  1891—19772,  19773 
Johnson  &  Cropper,  1878 — 3444 
Johnston,  1888 — 8252 
Junkers,  1892 — 14317 

Justice  (Hale),  1887 — 11255 

—  (Backeljau),  1884—11361 

—  (Baldwin),  1890 — 12678 

—  (Osam),       1881—3415  ;      (Hale), 
1883 — 2192,  5265  ;  1885 — 10401 

—  (Taylor),  1886—4881 


KABATH,  1883—999 

Kaselowsky,      1890 — 4574  ;      1891 — 

11680 

Kelly,  1892 — 11598 
Kempoter,  1885 — I58i 
Ken  worthy  and  anr. ,  1879 — 34^7 
Kerr,      1891 — 21496  ;     1892 — 17427 

l893~ 3332,  397i.  10310 
Kesseler,  1880 — 4159 
Key,  1891 — 6949 
Kidd,  1876 — 1034 
Kierzkowski,  De,  1876 — 3191 
Kinder  &  Kinsey,  1867 — 499 
King,  1879-4337  ;  1881—4223  ;  1883 

—638  ;    1884—7284-7288  ;    1885— 

1478,  1700 
King  (Connelly),  1890—5621 ;  1891— 

14002 

Kiichenpauer,  1883 — 3272,  5042 
Kirkhove  and  anr.,  1881 — 3561 
Kirkwood,  Lascelles  &  Hall,   1874— 

4410 
Knight,    1887—2783,    13555 1  1888— 

9691 ;    1889—6831 ;    1891—20926  ; 

1892-23323 
Korting,     1883—2702;  1887—12863; 

1888—17167 
Kortung,  1881 — 2931 
Kortynski,  1888 — 6468 
Kosakoff,  1887—12696 
Kostovitz,  1888 — 8273 
Krauss,  1879 — 3°9 


LADD,  1883—4242 

Lake  (Backeljau),  1893 — 5256 

—  (Beckfield     &     Schmid),     1890— 
2647 

—  (Beuger),  1888—5204 

—  (Brayton),  1890 — 11062 

—  (Breittmayer),  1880—3140 


$40 


The  Gas  Engine 


LAK 


MID 


Lake  (Fogarty),  1873—3848 

—  (Foster),  1872—387 

—  (Gardie),   1883—3383 

—  (Lay),    1878—4782,  4987  ;  1880— 
2182  ;   1881—4830 

—  (Maxim),  1883 — 132 

—  (Schmidt),  1872 — 3228 

—  (Secor    Marine     Propeller    Co.), 
1889—5165 

—  (Spiel),  1888 — 5914 

—  Wertheim),  1877 — 1063 

—  W.   R.,   1872—387,  3228;   1873— 
3848 

Lalbin,  1888—16268 
Lallement  and  anr. ,  1881 — 3113 
Lanchester,     1889 — 12502,       19868  ; 

1890—5479,  19513,    19775'   J9846  • 

1891 — 4222,  11861,  14945,  21406  ; 

1892—4210,  4374 
Lane,  1887 — 12591 
Langensiepen,  1893—4327 
Langen  &  Otto,    1866—434  ;  1867— 

2245 

Langou  (Marlin),  1893 — 2596 
Larrivel,  1888 — 13414 
Lascelles,  C.  F.  E.,  1874—3257  ;  1876 

-1961 

Laurent,  1882 — 6130 
Lawart  and  anr.,  1881 — 1074,  45^9  J 

1882—1868 
Lawson,    1880—3913  ;  1884—13935  ; 

1889—7640 
Lea,  1887—13436 
Lee,  1891 — 18424 
Leichsenring,  1878 — 3056 
Leigh     (Spiel),    1886—2272,      6165  ; 

l8Q2 2854 

—  (Forrest  &  Gallice),  1891—22559 
Leggo,  1871—2254 

Lenoir,  1883 — 5315  ;  1885—610 

Lentz  and  ors. ,  1890 — 21165 

Lesnard,  1869 — 1748 

Levasseur,  1891 — 9006 

Levassor,   1881 — 2765 

Lieckfeld,  1883—2702 

Lindahl,  1893—8158 

Lindemann,       1889 — 16391  ;    1891 — 


Lindley,       1882—703  ;    1883 — 3568  ; 

1887—2520,      11345  ;    1888—7547, 

16057;  1889—20033 
Lindner,  1890 — 1150 
List,  1887 — 12696 
List  &  ors. ,  1893 — 7433'  12388 
Livesey,  1880 — 2299,  5130 
Lobet,  1890 — 1979 
London   Economic    Motor  and  Gas 

Engine  Co. ,  1886—12068 


Love,  1891— 5250 

Lowne,  1889 — 17344 

Lucas,  1881 — 3527 

Luedeke,  J.  E.  F.,  1857—2408 

Luiford,  1876 — 2824  ;  1877 — 1470  ; 
1878 — 942  ;  1879 — 1500  ;  1880 — 
330;  1881 — 2990  ;  1883 — 326  ;  1884 
—5797 


M ABACK,  1892—16308  ;  1893—16072, 

16985 

Macallum,  1886 — 13517  ',  1891 — 816 
MacFarlane,  1880 — 4547 
Macgeorge,  1885—6880 
MacGillivray,    1882—3819  ;     1884— 

14765 

Mackenzie,  1885 — 3917 
Macneil,  T.  T.,  1866—27 
Magee,     1884  —  9544;     1885—6763, 

11422  ;  1886—665  ;  1892 — 9674 
Malam  and  another,  1880—1692,  3685 
Malandin  and   another,   1884 — 3986, 

6652,  15248  ;   1885—15710;  1886— 

ii  ;  1888 — 2805  ;  1890 — 14900 
Marchant,  R.    M.,    1874 — 5°9  '•  ^74 

—3189,  3190  ;    1883—1501 
Marcus,  1882 — 2423 
Marshall,  1860 — 2743 
Martaresche,  1887 — 2194 
Marti  and  another,  1882 — 5042 
Martin,  1893 — 2596 
Martini,  1883 — 1060 
Matteucci   &    Barsauti,    1854 — 1072  ; 

1857 — 1655  ;  1861 — 3270 
Maxim,  1883 — 132 
Maynes,  1882 — 5510 
Me  Allen,  1889—13572 
McDowall,  1887 — 4403 
McGhee,    1885 — 6763  ;     1886 — 1433, 

14578;  1887—11678;   1888—3427; 

1890 — 12690  ;  1891 — 19086  ;  1893 — 

1277 

McMillan,  1889 — 5397 
McNeill,  1884-6784 
McNett,  1889 — 12045 
Meekins,  F.  M.,  1859—784 
Melhuish,  1890—5192 
Mellin,  1893 — 2523 
Menard,  1891 — 12981 
Menzies,  1888 — 16605 
Merlanchon,  1863 — 1449 
Mewburn,  (Goubet),  1882 — 5506 

—  (Prowell  and  others),  1890 — 7177 
Michael,  H.,  1860—878 
Michels  (Grob),  1892 — 5819 
Middleton,  1887 — 14269;  1888 — 9725; 

1890 — 16301 


r  'Name  Index 


541 


MIL 


PRI 


Milburn,  1886 — 2993 

Miller,  1889—2637  ;  1891 — 834,  21529 

Millet,  1889 — 5199 

Mills,  1883 — 5721  ;  1885—5971 

Mills   &   Haley,    1875—265;    1877— 

3024  ;  1879—5052 
Montelar,  1881 — 5534 
Moram,  1892 — 6655 
Morcom,  1893 — 8095 
Morgan,  1893 — 12732 
Morris,  1888 — 11161 
Mottershead,  1890—17299 
Muirhead  and  another,   1881 — 4407; 

1882 — 1717 
Muller,  1880—4819 
—  and  others,  1884 — 16634 
Munden,  1884 — 4591 
Myers,  1884—848 


NASH,  1883—2561,  5543,  5632,  5633 ; 

1885  —  14394;    1886  —  493,   6670; 

1888 — 10350 

Nasmyth,  J.,  1859 — 1227 
Nelson,  1888—8009  ;  1889 — 5397 
Newhall,  1887 — 516 
Newman  and  another,  1881 — 1388 
Newton,  A.  V.,  1852 — 14150;  1855 — 

562 

—  (Murray),  1886 — 13727 
Newton,  1884 — 15633  ;  1885 — 7929, 

8583 
Newton,  A.  V.  (Emery),  1867— 

Newton,  W.    E.    (Marshall),   1860— 

2743 
(Barsauti  &  Matteucci),  1861 — 

3270 

(Babbitt),  1867—3690 

(Bisschop),  1872 — 1594 

Newton  &  Cowper,  1879 — 1947 
Neil,  1882—1026;  1883—3135  ;  1886— 

4234;    1887  —  11567;    1889  —  875, 

17295;  1893-14546 
Niemczik,  1891—8821 
Niepce,  J.  C.,  1817 — 4179 
Nixon,  1886 — 7658 
Nobbs,  1882 — 2257 
Noble,  1892 — 919 
Normandy,  A.  L. ,  1867 — 633 
Norrington,  1884 — 10062 
Norris,    1890  —  11755;   ^92  — 

4352,  4375 

Northcott,  1880—3176 
Nuttall  and  another,    1880  —  1969  ; 

1881— 811  ;      1882—614;       1883— 

2517 


ODLING,  1882—5825  ;  1883—130 
Oechelhaeuser,    1888—2913 ;    1889— 

4710;  1892—14317 
Offen,  1890 — 13594 
Ogle,  1892—9448 
Okes,  1893—6453,  9216 
Oldfield,  1891—18715 
Ord,  1881—798,  3275 
Osan,  1881 — 3415 
Otto,  1876 — 2081;  1878 — 1770;  1881 

— 60  ;    1883 — 1677  ;    1890  —  4823, 

5273,  5275,  5972,  6113 
Otto  &  Crossley,  1877 — 491 
Ovars,  1890—13352 
Owen,  1892 — 6240  ;  1893 — 7023 


PALMER,  T.  N.,  1872—1126 

Park,  1884 — 5435 

Parker,  1884 — 13776 

Partridge,  1889—6161 

Pascal,  J.  B.,  1861—166 

Pass,  De,  1881 — 2931 

Paton,  1889 — 441;   1892 — 17732 

Peebles,  1893 — 10801 

Perrett,  1886—2653 

Perrollaz,  1891 — 20845 

Pettit,  1892—260 

Philippi,  1883 — 3272 

Pickering,  1883—3708 

Picking    and    another,    1879 — 3561  ; 

1883—2492,  5406 
Pieper,  1891—19772,  19773 

—  (Krauss),  1879 — 309 

—  (Korting  and  another),  1883 — 2702 

—  (Schaeffer),  1878—290 
Piercy,  1884—5797 

Piers,  1888—10983,  10984;  1889— 
2144;  1892—15247 

Pinchbeck,  J.,  1865 — 905 

Pinkney,  1881—2645  '•  1885—1218  ; 
1887—1986  ;  1888—19013  ;  1889— 
3525  ;  1890 — 17167  ,  1891 — 103, 

7313,  11138,  17955 ;  1892—3203, 

20683  ;  1893—22753 
Pinkus,  H. ,  1839—8207  ;  1840—8644 
Plessner,  J.    M.,   1870—194;  1871 — 

2587 

Pollock,  1884—4639  ;  1892 — 8401 
Pope,  1885—3471 
Porteous,  1882 — 2058 
Pottle,  1880—9 
Prentice,  1884 — X4512 
Priestman,  1885 — 10227  ;  1886 — 1304, 

16779;    1887—1454,   5951,    12432; 

1888  —  270  ;  1889  —  6682  ;  1891— 

3830,    4142,     oco;    1892—21342; 

1893—12843,  20808 


542 


The  Gas  Engine 


PRO 


SHA 


Prowell  and  others,  1890 — 7177 

Publis,  1889—1957 

Pullen,  1893 — 12917 

Purchas,  1888—11614 

Purnell,    1884 — 12431  ;  1888 — 10165  ; 

1891—7047 
Pursell,     1879 — 1727,    4396  ;     1880 — 

3869 


QUACK,  1883 — 4023  ;  1888—2466 
Quaglic  and  another,  1882 — 5042 
Quick  and  another,  1881 — 5575 
Qurin,  1893—16290 


RACHOLZ,  1883 — 4193 
Rademacher,  1892 — 21917 
Ramsbottom,  1878—228 
Rankin,  1892 — 826 
Rapier.  1883—5928 
Ravel,  1887—16257 
Reddie  (Murray),  1884 — 12714 
Redfern  (Gardie),  1886 — 6161 

—  (La  Socie'te'  Anonyme  des  Moteurs 
Thermiques  Gardie),  1892—16413 

—  (McDonongh),  1884—13283 

—  (Sack  &  Reunert),  1876 — 3370 

—  (Smye-s),  1885 — 11290 
Regan,  1884—16890 ;  1888—15448 
Reid,  1893 — 2523 

Rennes,  1891 — 6727 

Repland  (Niel),  1889—875 

Reynolds,  J.  W.  B.,  1844 — 10404 

Rhodes,  1881 — 5259 

Rhodes  and  others,  1880 — 4398 

Richards,  1888—15158 

Richardson,  1890 — 11755  >  ^92 — 112, 

1768,  4347,  4352,  4375,  5972 
Ridealgh,    1887 — 4511  ;    1891 — 6598, 

10811 

Rider,  1879 — 2191 
Ridley,  J.  D.,  1874—777 
Rigg,  i8S5— 6047 
Rippingille,  E.  A.,  1868—3264 
Robert,  R. ,  1853 — 3^2  ;   1892 — 3574 
Roberts,  1877—711 
Robertson,  J.,  1868—3146 
Robinson,  J.,  1843 — 9972  '<  1880—117, 

2344,    4260,    5347;     1890—14787; 

1891 — 1083,  20262,   20745  >   !892 — 

9161  ;  1893—8864 
Robson,    1877 — 2734  ;     1879 — 4S01  • 

1880—4-150  ;    1881 — 2083  ;    1883 — 

5331  ;  1886—15307  ;  1890—9496 
Rockhill,  1884 — 2289  ;  1886 — 13655  ; 

1891—3669 
Rogers,  1885—15737;  1889—10286 


Rogerson,  1884 — 2088 

Rollason,  1886—7427,  12368  ;  1888— 
3546  ;  1889 — 16434  ;  1892 — 1879  ; 
1893—5005 

Rook,  1886—1696 

Roots,  1886—8210;  1888—9310,9311, 
11067,  15882,  16220  ;  1889 — 3972, 
9834  ;  1890—14549,  19559  ;  1891— 
18621,  19275  ;  1892 — 23786,  24065  ; 
1893—9618,  22181,  23571 

Ross,  1887—4403 

Rotten,  1889 — 17024 

Rousselot,  J.  S.,  1857 — 1754 

Rouzay,  1891 — 2815 

Rowden,  1888 — 9705 

Royston,  1885—13623 ;  1888—14614 

Ruckteschell,  1885—15475 

Russ,  1882 — 2231,  5371 

Russell,  1892 — 18118 

Russom,  1883 — 3041 

Rydill,  G.,  1873—329 

Ryland,  1893 — 20007 


SABATIER  and  others,  1893—608 
Sack  &  Reunert,  1876 — 3370 
Sanborn,  1892—16365 
Sayer,    1890—18161;     1892—13939; 

1893 — 6204 
Schaeffer,  1878—290 
Schiersand,  1890—11834 
Schiltz,     1881 — 3330;       1883 — 4455; 

1885 — 12896;   1886—10480 
Schimming,  1889—4796 
Schmid,  1887 — 14952 
Schmidt,  1872 — 3228 
Schmitz,  E.  N.,  1871—1724 
Schnell,  1888—7893 
Schollick,  E.  J.,  1853—1248 
Schoufeldt  and  another,  1881 — 1382 
Schultze,  1891—8821 
Schwarz,  1892  —  1814 
Schweizer,  1883—836 
Scollay,  1890 — 2207 
Seage,  1890—8431 
Seal,  1891 — 18621 
Seaton,  1882 — 2751 
Seek,  1891—22834  ;  1892 — 10091 
Secor  Marine  Propeller  Co.,  1889— 

Sennett,  1892 — 7943,  23800 

Serrell,  1883—4242 

Settle,  1891 — 12330 

Shann,  1884 — 6597 

Sharpneck,  1890—18645 

Shaw,  R.,  1867 — 422;  1879—392; 

1881—5178  ;  1886—2447  ;  1888— 

18377  ;  1891—18020 


Name  Index 


543 


SHE 


WAL 


Shepard,  E.  C.,  1850—13302 
Sherrin,  1893 — 18152 
Shiels,  1891—17033  ;  1893—779 
Shillito  (Capitaine),  i8b6 — 1797 

—  (Grob  and  others),  1891 — 8821 

—  (Swiderski   &   Capitaine),     1892 — 
6872 

Shuttleworth  and  others,  1893—531, 

17784 
Siemens,  C.  W.,  1862—2143  ;  1881— 

.2504.  5350 
Simms,  1893 — Z5947 
Simon,      1876—3435 ;      1877—2749 ; 

1879— 3233 ;    1885—1363 ;    1888— 

16183  ;  1892 — 926 

—  &  Miiller,  1877—2621 

—  (Kindermann),  1877 — 4937 

—  (L.  and  R. ),  1878 — 433 

—  and  another,  1878 — 4979 

—  (Todt),  1879-750 

—  &     Wertenbruck,       1880—4881  ; 
1881 — 4288 

Sington,  1887—4564 ;  1888—512 

Sitton,  1893 — -24612 

Skene,       1882 — 1590  ;       1884 — 454 ; 

1886—2174;  1891—5747 
Skinner,  1882—1910 
Smith,  1882 — 4418  ,  1889 — 2772 
Smithurst  and  others,  1893—14212 
Smyth,  W...  1867—1392 
Smyth  and  Hunt,  1875 — 2334 
Snelling,  1889—20703 
Snoxell,  1892 — 3417 
Snyers  and  another,  1881 — 3561 
Sohnlein,  1892 — 17391 
Sombart  (Buss),   1879—1933 

—  1880—1736  ;    1881 — 320  ;    1882 — 
2057 ;  1883 — 5923  ;  1884 — 8232 

Soul,  M.  A.,  1872—821 

Southall,  1885—12424  ;  1886—15472  ; 

1888 — 7934  ;    1889 — 5072  ;    1891 — 

9038  ;  1892 — 1203,  18020,  18109 
Sowerby  &  Oilman,  1825—5150 
Spiel,       1881 — 4244  ;       1883—4008  ; 

1885 — 3414  I      1886 — 2272,     6165; 

1887—3109 ;     1888—5914  ;    1892— 

2854  ;  1803 — 16410 
Stallaert,  1890—12760 
Steel,  1883 — 1116 
Stern  and  others,  1881 — 3536 
Sterry,  1887 — 125 
Stevens,  B.  F.,  1864 — 1599 
-  1887—4843 
Stitt,  1888—6794 
Stoke,  1893 — 23175 
Stout  and  another,  1885 — 11555 
St'eet,  R. ,  1794 — 1983 
Strok,  1892—18808 


Stuart,  1886—9866,  15319 ;  1888— 
10667,  14076;  1889—14868  ;  1890— 
7146,  12472,  13051,  15994  I  1892— 
3909,  22664 

Stubbs,  1888 — 7927 

Sturgeon,  1885 — 8897;  1887 — 4923, 
7925,  16309,  17353 

Sudlow,  W.  E. ,  1873 — 272 

Sumner,  1882 — 1360;  1889—7522, 
7533 

Susini,  De,  1892 — 14713 

Swiderski,  1892 — 2495,  6872 

Switz  and  others.  1893—23735 

Syers  &  Ellerback,  1875 — 


TAVERNIER,  1887 — 4757  11888—5628; 

1889—1603;  1889—7069 
Taylor,  1886—15327;  1889—708 
Teichmann,  1882 — 2008 
Tellier,   1887 — 2631  ;  1889 — 7*4° 
Thacker,  1876—88 
Theerman,  1890—1586  ;  1889 — 5301 
Thomas,  1887 — 2368 
Thompson  (Covert),  1889 — 12472 

—  (Durand),  1888—6088 

—  (Diirr),  1893 — 14572 

• —  (Geisenberger),  1880—533 

—  (Marcus),  1882—2423  ;  1883 — 2790 

—  jO'Kelly),  1882—11598 

—  (Regan),  1888 — 15448 
Ticehurst,  1891—8251 
Tipping,  1893—16079 
Tomkin,  1881 — 5201  ;  1883 — 5976 
Torassx,  C.  J.  B.,  1856—1807 
Touche,  La,  1890—2384 
Townsend,  1883 — 781 

Tracy,  1887 — 1168,  12749 
Treeton,  1885—8584 
Trewnella,  1891 — 3948  ;  1893 — 5456 
Turner,  F.  W.,  1873—4088  ;  1879— 

1270  ;      1880 — 3182  ;      1882 — 362  ; 

1884 — 16698  ;  1888 — 4057 
Turnock,  1887—8 


VANDUZEN,  1891 — 5158,  8032 
Vaughan,    E.    P.    H.,     1870 — 1352, 

2959 

Vera,  P.,  1875—175 
Vermand,  1890 — 13019 
Villeneuve,  A.  H.,  ib7o — 440 
Vogelsang,  1890 — 10642 


WALCH     (Dorrington    &     Coates), 

1891—18276 
Wallace,  1884—10364 


544 


The  Gas  Engine 


WAL 


YOU 


Walker   and   another,    1832—6136  ; 

1893—7292 

Waller,  1878 — 2901  ;  7891—14457 
Wallwork,  1887 — 4940,  7925,  17353 
Warsop,  1885 — 7104 
Wastneld,     1881—2967 ;    1882—659, 

4755-     4773  I    1883—1098,     5956  ; 

1887-7771 

WTatkinson,  1891 — 14134 
Watson,  1881—1723,  1763,  2919,  4137, 

4608  ;  1882—678,  2342,   5782,  6214 
Wattles,  1893—23379 
Watts,  1882—4418 
Weatherhogg,     1878—3972  ;    1881 — 

4402  ;  1883 — 499  ;  1884—4880  ;  1885 

— 6565  ;  1886 — 8436  ;  1889—8013  ; 

1891—1447 

Webb,  J.,  1853 — 1577;  1892 — 11928 
Weigand,  1884 — 6662 
Weilbach,   1888—15858  ;  1889—3887 
Weiss,  1891 — 3261 
Welch  and  another,  1883 — 5928  ;  1886 

—1696 

Welford,  1891—6598 
Wellington,  1891 — 11851 
Wenham,  F.  H.,  1864—1173  ;  1881— 

867 
Wertenbruch,      1880 — 4881 ;    1881— 

4288  ;  1891—3682 
Wertheim,  1877 — 1063 
Wettor  (Rademacher),   1892 — 21917 
—  (Gerson  &  Sachse),  1893 — 153 
Weyhe,  1877 — 4052 
Weyman,        1891 — 18640,         21015, 

21229  •   1892 — 11141,  154171  2o56o, 

22797;   1893—2912 
Wharry,  1889—10286 
White,  1890—16301 
Whitehead,  1883 — 1116,  2927 
Whittaker,        1882—5819 ;       1892— 

16986 
Wigham,    1879 — 4485  ;    1880—5269  ; 

1881—2564 

Wilcox,  1885 — 15874,  15875,  15876 
Williams,    1879—4340;    1881—3715, 


5456;  1883 — 300,  3069;,  1887— 
16029,  16144  I  l888 — 10469.  I483I  : 
1889—3820;  1891 — 970,  1299,  15078 

—  and   another,     1880—1692,    3685  ; 
1883—4816 

—  and  Baron,  1879—2 
Williamson  and  others,   1883—4816, 

5570;   1884 — 9167;   1885—1478 
Wilkinson,  1890 — 10051  ;  1892 — 524  ; 

1893—8409 
Wilson,    1880—3652 ;    1884—12776  ; 

1888—4944 

—  and  others,  1871—3121,  3122  ;  1878 
—4760 

Wimshurst,  1885 — 15936 

Winckler      (Jastram),      1892 — 21857, 

21858 

Windisch,  1893—15900 
Wirth      (Humboldt      Manufacturing 

Co.),  1876 — 1520 

—  (Bernstein),  1884 — 1457 

—  (Sohnlein),     1883—5297 ;     1884— 

4736 

Withers,  1882—417  ;   1891 — 9931 
Witlig  and  Hees,  1879 — 3732 
Wolstenholme  and    another,    1882 — • 

2753 ;    1885—8160  ;    1886—15507, 

i55°7A 

Woodhead,  1883—21 ;  1884—2715 
Woolfe,  1879 — 2I52 
Wordsworth,      1880—2181  ;      1882— 

703  ;  1887—11466  ;  1888—7521 

—  and  others,     1881 — 4340;     1882 — 
2753;     1883—3568;       1885—8160; 
1886—15507  ;  1886— 15507 A  ;  1888, 
— 11161 

Worssani,  1882—2126 
Wrede,  F.,  1853—1648 
Wright,  L.  W.,  1833—6525 

—  and  another,  1885 — 1703  ;     1886 — 

6551 
Wrigley,  1883—1501 


YOUNG,  J.,  1872—2293 


545 


GENERAL    INDEX 


ABE 

ABEL,  SIR  FREDERIC,  on  gun-cotton 
explosions,  88 
—  flash  test  apparatus,  395 
Absolute      indicated      efficiency      of 

Crossley  Otto  engines,  376 
Absolute  efficiency,  increase  of,  384 
Acme  compound  engine,  332-339 
Actual  indicated  efficiency,  117 
Adiabatic  line,  40 

on  Atkinson  diagram,  281 

and  isothermal  expansion   dia- 
gram, 384 

Admission   velocity  of  gases  in  old 
type  Otto,  305 

—  velocity  of  gases  in  modern  type 
Otto,  306 

Advantages  of  scavenging,  380 
Air,  compression  lines  for,  40 

—  required  in  combustion  of  Dowson 
gas,  365 

—  suction    silencer    for    'Stockport 
Otto,'  318 

—  supply  drawn  through  vaporiser  in 
oil  engines,  471 

—  supply  to  Crossley  oil  engine,  434 

—  engine,  Ericcson's,  24 

—  Joule's,  31 

Rankine  on,  24 

• Stirling's,  25 

—  Wenham's,  25 
Air  and  gas  mixtures  : 

—  proportion  of,  99,  100   101 
-  —  in  Clerk  engines,  193,  195 

Lenoir  engines,  128,  252 

—  Otto  engines,  173,  176 

—  Otto  and  Langen  engines,  147 
Allen's    analysis   of  petroleum  ether 

and  spirit,  393 

American  petroleum,  composition  of, 
389 


- 


ATK 

Analysis  of  coal  gas  : 

Berlin,  271 

Chemnitz,  271 

Deutz,  172 

Hoboken,  175 

London,  271 

Manchester,  109 

Natural  gas,  272 

New  York,  271 
Analysis  of  Dowson  gas,  363,  364 

—  of  Lencauchez  producer  gas,  370 

—  of  coal  used  in  American  gas  pro- 
ducer, 373 

—  of  Scotch  paraffin  oil,  414 

—  of  Russoline  oil  by  Prof.  Wilson, 

425 
Andrew  &  Co.,  J.  E.  H.,   Stockport 

Otto  engines,  318-324 

low  pressure  starter,  352 

Anthracite,  consumption  of,   in  gas 

producer,  372,  373 
Apparent  indicated  efficiency,  117 
Apparatus  for  distilling  oils,  402 

oil  by  air  or  steam,  405 

Applications    of   petro'eum  engines, 

459 
Atmospheric  engines — 

Barsanti  and  Matteucci,  n 

Brown's,  2 

Gillies',  15 1 

Otto  and  Langen,  136 

Wenham's,  35 
Atkinson's  differential  engine,  195 

—  cycle  gas  engine,  273-284 

—  engine  :  diagrams  of  linkage,  276 

—  Society  of  Arts  test,  280 
number  of,  in  use,  283 

—  '  Utilit^ '  gas  engine,  284-286 

—  Crossley  Otto  scavenging  arrange^ 
nient,  313,  314 

N  N 


546 


The  Gas  Engine 


ATK 


CLA 


Atkinson's  test  of  Crossley  scavenging 

engine,  318 
Atkinson  on  increased  compression, 

379 

Attempts   at   compounding    gas    en- 
gines, 332 

Available  heat,  definition  of,  112 
Average  pressure  less  in  oil  engines, 

465 

—  consumption  of  anthracite  in  pro- 
ducers, 374 


BARNETT'S  compression  engines,   5, 

6'  9.  . 

—  igniting  cock,  7,  207 
Barsanti  and  Matteucci  engine,  n 
Barker's,  T.  B. ,  Otto  engine,  324-329 

—  Otto  engine  tests  of,  at  Saltley  gas 
works,  329 

Beau  de  Rochas  on  compression,  17 
Berthelot,  on  calculation  of  tempera- 
tures, 1 08 

—  explosion  pressures,  106 
—  wave,  114 

—  time  of  explosion,  114 
Berthelot  and  Vieille,  explosion  wave, 

87,  88 
Beechey,   Mr.,    'The  Fawcett  '    gas 

engine,  293 
Bellamy,  Mr.  A.   R. ,  experiments  on 

increased  compression,  321-322 
Bellamy's  experiments   on   increased 

compression,  379 
Bischoff  engine,  132 
Birmingham  Corporation,  tests  of 

Barker  Otto  engines,  329 
Bousfield  on  stratification,  250 
Boyle's  law,  38 
Brake,  tests  of  : 

—  Brayton  engine,  157,  159 

—  Clerk  engine,  191-4 

—  Otto  engine,  172,  175,  180,  181 

—  Otto  &  Langen  engine,  141 
Brayton  engine,  20,  32,  152 
tests  of,  157,  159 

• ignition,  217 

—  governor,  233 

—  petroleum  pump,  156 
Brayton  oil  engine,  407 
Britannia  oil  engine,  449-453 
Brown   and   Steward's   trial   of  Otto 

engine,  175 

Brown's  gas  vacuum  engine,  2 
Brox  bourne  oil  used  in  Crossley  oil 

engine,  438 

Bunsen   corroborates  Davy's  experi- 
ments, 83 


Bunsen  on  explosion  pressure,  106 

velocity  of  rlame  propagation, 

84 

highest  temperature  of  combus- 
tion, 93 

dissociation,  257 

Bunsen  burner,  action  of  in  varying 
time  of  ignition,  328 

—  blue  flame  lamp,  the  Etna,  431-433 

—  from  petroleum,  419 
Burt's   compound  Otto  engine,  332- 

339 

—  tests  by  Professor  Jame- 
son, 338 

—  test  by  Professor  Rowden , 
338 

—  Otto  engine,  339 

—  test  of,  339 

—  high  speed  Otto  engine,  340-342 


CALORIFIC  intensity,  90 

—  power,  90 
Campbell  gas  engine,  286 

—  oil  engine,  445-449 

Capper,    Professor,    test  of  Hornsby 
Ackroyd  oil  engine.  424-426 
—  Capitaine  oil  engine,  428 

Capillary    attraction,    use   of,    in   oil" 
engine  lamp,  418 

Charles's  law,  38 

Chemistry  of  petroleum  and  paraffin 
oils,  388-406 

Chemical  reactions  in  gas  producing, 

356-3S9 
Classification  of  gas  engines,  29 

oil  engines,  408-409 

Clerk  engine,  184 
—  tests  of,  191-4 

—  igniting  valves,  215,  217,  223 

—  governor,  233 

—  starting  gear,  first,  238 
Clerk's  explosion  experiments,  95 
Clerk,   Crossley  starting   gear,    347- 

348 

—  Lanchester  starting  gear,  348-349 

—  cycle,  engines  following  the,  286 

—  heat-balance   sheets    in    Hornsby 
Ackrovd  engine,  426 

—  Dugald     tests     of    Crossley    sca- 
venging engine,  316 

—  Dugald  tests  of  early  and   modern 
Otto   Crossley  engines,    1881    and 
1892,  308,  309 

Clerk's  (D.)  tests  of  gas  engine  and 

producer,  374 
Clarke,      Chapman      &      Co.'s     oil 

engine,  453-455 


General  Index 


547 


CLI 


.Clifton      Rocks      Railway      'Otto' 

engine,  297-305 
Clutch,  Otto  £  Langen,  140 
Combustion  and  explosion,  79 

—  heat  evolved  by,  89 

—  volume  of  products,  82 
Combustion     space      '  Trent '      gas 

engine,  288 
—  shape  of,  290 

—  chamber,     shape     of,     in    Tangye 
engine,  330-332 

—  space,  peculiar  arrangement  of  in 
Hurt's    high    speed     Otto   engine, 
34i 

of  Dowson  gas,    heat   evolved 

by,  366 

—  chamber    used     as     a     vaporiser, 
Hornsby  Ackroyd  oil  engine,  420 

and    vaporiser    of    Robey    oil 

engine,  427 

—  Capitaine  oil  engine,  427-429 

—  chamber    walls,    temperature    of, 
468 

Combining  weights,  80 
Compression  engines- 
Atkinson's,  197 

Barnett's,  5,  6,  9 
•   Brayton's,  20,  32,  152 

Clerk's,  184 

Million's,  16 

Otto's,  172 
.    Siemens',  18,  32 

Stockport,  197 

Tangye's  (Robson's),  195 
Compression,  Barnett  on,  5 

—  Beau  de  Rochas  on,  17 

—  Jenkin  on,  214 

—  Million  on,  16 

—  Schmidt  on,  17 

—  Siemens,  proposed  by,  17 

—  Witz  on,  244 

Compressions  and  gas  consumptions 
in  early  and  modern  Crossley  Otto 
engines,  317 

—  value  of,  to  obtain  economy,  318 

—  increase    of,     Mr.     Bellamy's    ex- 
periments on,  321-322 

—  explosion     obtained      by     Clerk- 
Lanchester  starter,  349 

—  space,    importance    of  shape    of 
378 

—  increase  of,  the  cause  of  economy 
376-386 

Comparative  table  of  old  and  new 
type,  Crossley  Otto  engines,  310 

—  table      of      Crossley     Otto      gas 
consumptions    and    compressions, 
3*7 


DAV 


Comparison  of  ico-h.p.  steam  and 
gas  engine  in  cost  of  power,  354 

—  of  gas  for  motive  power  and  for 
illumination,  355-56 

Comparative  values  of  hydrogen 
and  carbonic  oxide  for  motive 
power,  364 

—  table     of    theoretic     and     actual 
efficiency,  377 

—  diagram  of  Crossley  Otto   engines 
with  different  compression  spaces, 
378 

—  table  of  efficiency,  383 
Comparison  of  oil  engines  of  different 

types,  473 

Complete  producer  plants  for  8o-h.p. 
gas  engine,  361-362 

—  combustion       in       oil       engines, 
necessity  for,  ^88 

Compound    engine,   the   Burt   Acme 

engine,  332-339 
—  principles  advisable,  386 
Condenser,    excessive     port     surface 

acting  as  a,  307 
Conditions  of  gas   engine  economy, 

34i 

—  of     cuccessful     compet  tion     with 
sttam  engine,  356 

Constructional   defects    in    Atkinson 

Cycje  engine,  283-284 
Consumption     of    fuel     in     Dowson 

producer,  371-374 
Corliss  type  of  gas  engine  by  Messrs. 

Robey,  342-344 
Critical  proportion  of  gas  in  mixture, 

83 

Crossley  Otto  engines,  297-318 
power  of,  297 

—  increase    in     economy     of 
297 

1892  engine  governing  gear   301 

3°3 

—  igniting  valve  and  tube,  302, 
3°5 

—  engine,  tests  of,  308,  309 

—  engines,    comparative   table   of 
old  and  new  types,  310 

scavenging  engines,  309-317 

—  engine,    te.t    by    Atkinson, 
318 

oil  engine,  430-439 

Crude  petroleum,  388,  389 
Cushion  of  inert  gases,  247,  248 
Cycles  of  action,  29-35 

DAIMLER  oil  engine,  460-461 
Davy,  Sir  H.,  on  inflammability,  82 

N  N  2 


548 


The  Gas  Engine 


DAY 


DOW 


Day  gas  engine,  the,  290-293 
Decomposing     ard     vaporising    oil, 

methods  of,  398-406 
Decomposition  of  heavy  oils,  403 
Defects    in     construction,    Atkinson 

cycle  engine,  283,  284 
—  of  slide  valves  in  gas  engines,  304- 

3°5 
Design,   gas  engine,   leading   factors 

in,  306-307 
concerning  ports  and  passages, 

325-328 
Destructive   distillation,    effect   of  in 

gas  production,  356 
Deutz  coal  gas,  172 
Dewar  and   Redwood's    method     of 

distillation,  404 
Diagrams,  indicator  : 

Bischoff,  134 

Bray  ton,  158,  160 

Clerk,  192-5 

Hugon,  132 

Otto,  177,  179,  181 

—  Otto  and  Langen,  142, 147,  148, 

150  T 

Lenoir,  124,  125, 

—  Simon,  164 

-  ^.ei  feet  theoretical : 
type  i,  43 

2,  47 

3,  50,  52,  54, 
i  A,  54 

—  of  Atkinson  cycle  engine  linkage, 
276 

—  indicator   comparative   Otto    and 
Atkinson  '  Cycle'  engines,  279 

Atkinson  cycle  engine,  Society 

of  Arts  tests,  280,  281 

from  Trent  gas  engine,  289 

from  Day  gas  engine,  292 

(Modern  Crossley  '  Otto'),  308 

—  (Slide  valve,  Crossley  '  Otto  '), 

3°9 

—  of  valve  setting   in   Crossley   sca- 
venging engine,  315 

—  indicator    4-n.h.p.    Crossley    sca- 
venging engine,  316 

from  '  Stockport  Otto '  321,  322 

—  Barker  Otto  engines,  329,  330 
Burt's  compound  Otto,  338 

—  Otto  engine,  339 

—  high  speed  Otto,  342 
Diagrammatic    section,    Clerk    Lan- 

chester  starter,  349 
Diagram,  indicator,  from  Otto  engine 
using  Dowson  gas,  374 

—  comparative,     Crossley    Otto   en- 
gines, different  compressions,  376 


Diagram,    theoretical,   adiabatic  and 
isothermal  expansion,  384 

—  indicator     from      Priestman     oil 
engine,  417 

—  of  ignitions  at  low  temperature, 
422 

Diagrammatic  section,  Clerk  Crossley 

starting  gear,  348 
Diagram    indicator    from     Hornsby 

Akroyd  engine,  426 

—  from  Robey  oil  engine,  428 

• from  Clerk  Lanchester  starter, 

350 
Diagrammatic     section,     Lanchester 

low-pressure  starter,  350 
Diagram,  indicator  from,  Lanchester 

low-pressure  starter,  351 

with  coal  and  Dowson  gas,  382 

from  Crossley  oil  engine,  438 

—  —   from   Fielding   and   Platt   oil 
engine,  444 

from  Campbell  oil  engine,  4.48 

from  Britannia  oil  engine,  452 

• from  Weyman  &    Hitchcock's 

oil  engine,  458 

from  Wells  Bros.'  oilengine,  460 

Differential  engine,  195 
Difficulties  of  oil  engine,  462-473 
Dilution  of  mixtures,  83 
Dimensions     of    6-n.h.p.      Atkinson 

Cycle  engine,  277 

—  of  4-n.h.p.  Atkinson  Cycle  engine, 
278 

—  of  Burt's  compound  Otto  engine, 
336 

Dissociation,  Deville  on,  92,  93 

—  Bunsen's  theory  of,  257 

—  definition  of,  92 

—  Groves  on,  92 

—  Thurston  on,  178 

Distillation    of    solid    paraffin    with 
steam,  400 

—  of  oils,  experiments  in,  400-406 
Distilling  oil  by  air  or  steam,    appa- 
ratus tor,  405 

Dowson  plant  used  to  operate   400- 
h.p.  engine,  324 

—  gas  used  in  Wells  Bros.'  scavenging 
engine,  344,  345 

—  producer,  fuel  for,  354 

—  producer,  the,  359-376 
analysis  cf,  363-364 

• heat  evolved  by  combustion  of, 

366 
producer,  consump  ion  of  fuel, 

37 1 

• —  producer  and   Otto  engine,    test 
by  D.  Clerk,  374 


General  Index 


549 


DRA 

Drake's  engine,  10 

—  ignition,  10 

Dulong  and  Petit's  law,  90 


EARLY  oil  engines,  407 
Economy,  the  result  of  increased  com- 
pression, 376-386 

—  due  to  scavenging,  379 
Efficiency,  definition  of,  37 

—  of  perfect  heat  engine,  39 

—  of  imperfect  heat  engine,  41 

—  formulae,  56,  57 

—  apparent  indicated,  117 

—  actual  indicated,  117 

—  of  gas  in  explosive  mixtures,  112 

—  of  Atkinson  cycle  engines,  283 

—  mechanical,    '  of       '  Trent '      gas 
engine,  289 

—  indicated,  of '  Fawcett '  gas  engine, 
290 

—  mechanical,   of  old  and  new  type 
Crossley  '  Otto '  engines,  310 

—  of  Dowson  gas  producer,  367 

—  Lencauchez  gas  producer,  370 

—  in  '  Otto '  engines,  gradual  increase 
in,  375-376 

—  absolute,  increase  of,  384 

—  comparative,  of  oil  and  gas  engine, 
462 

Efficiencies,  table  of,  68 

—  of  Brayton  engine,  162 

—  of  Clerk  engine,  192 

—  of  Lenoir  engine,  128 

—  of  Otto  engine,  172,  176 

—  of  Otto  and  Langen  engine,  141 

—  comparative  table  of,  383 

—  yet  possible  in.  gas  engines,  386 
Electrical  ignition,  203,  205 

—  in  Priestman  engine,  411 
— •  objectionable,  462 

—  lighting,  engines  for,  good  govern- 
ing method  in,  346 

Equivalent,  mechanical,  of  heat,  36 
Ericcson  engine,  fuel  used,  26 
Erroneous  heat  values  in  oil  engine 

tests,  425 

Eth«r,  petroleum,  and  spirit,  393 
Etna  lamp  type  used  in  oil  engines, 

431-433 
Evaporation  of  water  by  air,  399 

—  of  petroleum  by  air,  400 
Exhaust      gases,       temperature      of 

Lenoir,  122 

—  velocity  of,  in   old  type  Otto, 
306 

velocity  of,,  in  new  type  Otto, 


FLA 


Exhaust   pipe,   oscillations  or  waves 
of  pressure  in,  313 

—  valve,  arrangement  of  in  Robey's 
'  Otto  '  engine,  342 

—  heating    vaporiser    in    Priestman 
engine,  412 

—  valve    closed     during     governing, 

4J7 

—  valve  held  open  when  governing, 
448 

—  gases   heating   air    supply   in    oil 
engine,  453 

Expansion  of  gases  bv  heat,  38 

—  gas  engine,  332-339 

—  a  source  of  further  economy,  386 
Experiments   in    increased   compres- 
sion, Bellamy's,  321-322 

—  in     petroleum     and     shale     oils, 
Robinson,  397 

—  in  distillation  of  oils,  400-406 

—  with  ignitions  at  low  temperatures, 
422-423 

Explosion,  95,  115 

—  chemical  reactions  of,  81,  82 

—  Clerk's  apparatus,  95,  90 

—  combustion  and,  79 

—  observed  and  calculated  pressures, 
104,  106 

—  proportion    of   heat    evolved    by, 

H3 

—  premature  avoided  by  scavenging, 
380 

Explosive  mixtures,  true,  79-82 
efficiencies  of  gas  in,  112 

—  curves  of  cooling,  97,  98 

—  inflammability  of,  83 

—  pressures  produced  by,  99-101 

—  flame  propagation  in,  84-95 
temperature  produced  by,  107- 

iii 

—  volumes  of  products,  82 
External  vaporiser  oil  engines,  429— 

459 


FAWCETT  gas  engine,  the.  293-296 
Fielding   &    Platt's    '  Otto '    engines, 

346 
starting  gear,  353 

—  oil  engine,  442-445 
Flame  propagation  : 

—  Berthelot  and  Vieille  on,  87,  88 

—  Bunsen  on,  84 

Mallard  and  Le  Chatelier  on, 

85.87 
Flame,  temperature  of,  93,  94,   108, 

109,  no,  in 
—  theoretical  temperature  of,  91 


550 


The  Gas  Engine 


FLA 


GAS 


Flame,    temperature    of,    in    Lenoir 
engine,  126 

—  Brayton  engine,  161 

—  Otto  and  Langen  engine, 
146-149 

—  Otto  engine,  177,  179 

—  starting  gear,  the  Clerk  Crossley, 
347-348 

Flashing   point  of  British  sold  lamp 

oils,  394,  396 
Foster,  Professor,  analysis  of  Dowson 

gas,  363 
Free  piston  engines  : 

Barsanti's  and  Matteucci,  n 

Gillies',  151 

Otto  and  Langen,  10,  136 

Type  i  A,  66 

Wenham,  35 

French  analysis  of  Dowson  gas,  364 
Friction  of  Brayton  engine,  15 

—  —  Otto  engine,  174 
Furnace  engine,  Cay  ley,  25 
Wenham,  25 

—  loss  in  cylinder,  112 
Future  of  gas  engine,  260 

Fuel  for  Dowson  gas  producer,  354 

—  consumption  of  gas  engines  with 
producer  gas,  371 


GARRET'S   governor  (Clerk  engine), 

234 
Gas,  coal  analysis  of  ; 

Berlin,  271 

Chemnitz,  271 

Deutz,  172 

Hoboken,  175 

London,  271 

Manchester,  109 

Natural  gas,  272 

New  York,  271 
Gas  and  air  mixtures,  explosions  of, 

99,  loo,  101 

—  best  proportions  of,  101-104 
Gas,    consumption    of,    by     Bischoff 

engine,  134 

—  Atkinson  cycle  engine,  283 

—  Brayton  engine,  158 

—  Clerk  engine,  191-194 

—  g-n.h.p.    Crossley    Otto    1892, 
308 

—  6-n.h.p.  Crossley  Otto  1881,  309 

—  4-n.h.p.     Crossley     scavenging 
engine,  316 

-  '  Fawcett '  engine,  296 

—  Hugon  engine,  132 

—  Lenoir  engine,  124,  252 
Otto  engine,  172,  175,  180,  183 


Gas,    consumption   of,    by  Otto  and 
Langen,  141 

—  '  Trent  '  engine,  289 

Gas  consumptions,  comparative  table 
of,  in  Crossley  engines,  317 

—  Barker  Otto  engines,  329,  330 

—  Hurt's  compound  Otto,  338 

—  —  Burl's  Otto  engine,  339 

—  • —  Crossley  Otto  engines,  decrease 
n,  375 

Stockport  Otto  engine,  321-322 

-  Tangye  s  Otto  engines,  332 

—  Weils  Bros. '  Otto  engine,  346 

—  efficiency  of  in  explosive  mixtures, 
112,   113 

—  for  motive  power  and  illuminating 
gas,  355 

Gas  engine,  Atkinson  'Cycle,'    278- 
284 

—  Atkinson  '  Utilite",'  284-286 
The  '  Campbell,'  286 

—  Otto  Crossley  scavenging,  309- 

3J7 

The  '  Day, '290,  293 

The  '  Fawcett,'  293-296 

The  '  Midland, '•  287 

-  The  '  Trent,'  287-290 

-  The  '  Stockport  Otto,1  318-324 
The  Barker  Olio  engine,   324- 

329 

—  Otto  Tangye,  329-332 

—  The     Burl     Compound      Otto 
engine,  332-339 

—  Burl's  high  speed  Otto,  340,  342 

—  Robey's  Otlo,  342-344 

—  Wells  Bros.'  Olio,  344-346 

—  Fielding  and  Plait's  Otlo  engine, 
346    .  . 

giving  impulse  every  revolulion, 

286 
design,  leading  faclors  in,  306- 

3°7 

• comparalive  table  of  old  and 

new  lype  Crossley  Olto,  310 

—  the  largest  manufaclured,  322- 

324 

working    wilh     producer    gas, 

precaulions  required,  366 

—  and  producer,  consumplion  of 
fuel,  371,  373 

Gas,  Dowson,  volume  of  air  required 

for  combusdon,  365 
heal  evolved  by  combuslion  of, 

366 
Gas  produclion,   chemical   reaclions 

in,  356-359 
Gas  producers,  condilions  of  success, 

355 


General  Index 


551 


GAS 


IGN 


Gas  producer,  the  Lencauchez,  367- 

37° 
Gas,   Lencauchez  producer,  analysis 

of,  370 
Gas  producers,  Dowson,  359-367 

—  other  makers  of,  370 

—  Dowson,  fuel  for,  354 

Gas  producer  plant  for  80  h.  p.  engine, 
361-362 

—  Dowson,  analysis  of,  363-364 
Gay-Lussac's  laws,  82 

Gear  wheels,  disadvantages  of,  339 

Gillies'  engine,  151 

Glycerine  bath  for  oil  engine  pump, 

429 
Governors  of  Bischoff  engine,  226 

—  Brayton  and  Lenoir,  233 

—  Clerk,  234 

—  Lenoir  and  Hugon,  226 

—  Otto,  230,  231,  232 

—  Otto  and  Langen,  227 

—  Tangye  (Pinkney),  235 
Governing  in  Crossley  oil  engine,  433 

-  Tangye  oil  engine,  439-440 

—  Campbell  oil  engine,  447-448 

—  Britannia  oil  engine,  450 

—  Clarke  Chapman's  oil  engine,  455 

—  Wells  Bros.'  oil  engine,  457 

—  difficulties    in    Priestman    engine, 
466 

—  Samuelson  engine,  467 

—  Hornsby  oil  engine,  469 
Governor   gear    of    Crossley  '  Otto  ' 

1892  engine,  301-303 

Governing  arrangements  in  Fielding 
and  Plan's  Otto,  346 

Governor  gear  in  Priestman  engine, 
414 

Governing  arrangements  in  Samuel- 
son  engine,  416 

Griffin  patent  Samuelson  oil  engine, 
416-420 

Guilford,  Mr.  F.  L.,  tests  of  '  Trent ' 
engine,  289 


HAUTEFEUILLE'S,  Abbe",  engine,  i 
Heat,  available  definition  of,  112 
—  table  of,  113 

—  balance    sheets    of  Otto    engine, 
172,  176 

—  engines  perfect,  39 
—  imperfect,  41 

—  evolved  by  combustion,  88,  89 

—  balance  sheet  in  Society   of  Arts 
test  of  Atkinson  cycle  engine,  283 

—  evolved  by  combustion  of  Dowson 
gas,  366 


Heat,     balance-sheet     of     Hornsby 
Akroyd  engine,  425,  426 

—  mechanical  equivalent  of,  36 

—  losses  in  gas  engine,  72 

—  lost  through  surfaces  in  Otto,  172, 
176 

—  of  compression,  40,  270 

—  specific  of  gases,  90 

—  constant  volume,  89,  90 

—  pressure,  89,  90 

—  unit,  89 

Heating  value  of  Openshaw  gas,  375 

—  of  vaporiser   charge    in    Crossley 
Otto  oil  engine,  430 

—  air  supply  in  oil  engine,  advantage 
of,  442 

—  —  in  Britannia  oil  engine,  450 
Heavy  oils,  decomposition  of,  403 
High    pressure   starter,    Clerk    Lan- 

chester,  349 

—  speed  Utto  engine,  Burt's,  339— 
342 

Hirn's  experiments  in  explosion,  104, 

IOS 

—  theory  of  limit  by  cooling,  257 
Hoboken,  coal  gas,  175 
Hopkinson,    Dr.      John,     Judge     in 

Society  of  Arts  tests,  279 
Hornsby  Akroyd  oil  engine,  420-426 
Hot  air  engines,  Ericcson's,  2* 

—  Joule's,  25 

—  Rankine  on,  24 

—  Stirling's,  25 

—  Wenham's,  25 
Hugon's  engine,  20,  129 

—  igniting  valve,  209 
Huyghens'  gunpowder  engine,  i 
Hydrogen,  80,  82 

—  heat  evolved  by,  89 

—  mixtures,  84,  86,  87 

Hydrogen  and  carbonic  oxide,  com- 
parative values  of,  for  motive  power, 
364. 


IGNITING  arrangements,  209 

—  chemical,  225 

—  electrical,  203-207 
• —  flame,  207-221 

—  incandescence,  222-224 
Ignition,  varying  of,  in  Barker  Otto 

engine,  328 

—  arrangement     in    Samuelson     oil 
engine,  418 

—  of  oil  vapour  and  air  at  low  tem- 
perature, 422 

gas  and  air  at  oil  temperature 

422-423 


PS&  LiB^p 

X^         OF  THK         nr 


552 


The.  Gas  Engine 


IGN 


LEN 


Ignition  lamp,    type   in  use   in  low 
engines,  431-433 

—  in  Crossley  oil  engine,  435 

—  tube  and    vaporiser   combined  in 
oil  engine,  461 

—  in  Daimler  engine,  461 
Illuminating  gas  and  gas  for  motive 

power,  355 

Imray  on  stratification,  250,  254 
Inert  gas,  cushion  of,  247,  248 

—  diluent,  246,  247 
Inflammability,  82 
Inflammation,  definition  of,  99 
Indicator   diagrams,    theoretical,  43, 

47.  5°.  52-  54 

Comparative   Otto  and  Atkin- 
son cycle  engines,  279 

—  (Society  of  Arts  Atkinson  cycle 
engine),  280,  281 

('  Trent '  gas  engine),  289 

('  Day  '  gas  engine),  292 

(Modern  Otto  Crossley  engine), 

308 
(Slide     valve     Otto      Crossley 

engine),  309 

—  4-n.h.p.     Crossley     scavenging 
engine,  316 

—  from    '  Stockport    Otto,'    321, 
322 

—  Barker  Otto  engine,  329,  300 

—  Hurt's  compound  Otto,  338 

—  high  speed  Otto  engine,  342 
Otto,  engine,  339 

—  from  Clerk-Lanchester  starter, 

350 

—  Lanchester     low  -  pressure 
starter,  351 

—  from   Otto    engine  using  pro- 
ducer gas,  374 

from  engine  with  ordinary  and 

Dowson  gas,  382 

—  from  Priestman  oil  engine,  417 
of  ignitions  at  low  temperatures, 

422 

—  from  Hornsby  Akroyd   oil  en- 
gine, 426 

—  from  Robey  oil  engine,  428 

—  from  Crossley  oil  engine,  438 

—  from    Fielding    and    Platt   oil 
engine,  444 

from  Campbell  oil  engine,  448 

—  from  Britannia  oil  engine,  452 
from  Weyman  and  Hitchcock 

oil  engine,  458 

—  Wells  Bros.'  oil  engine,  460 
Indicated  efficiencies  in  Crossley  oil 

engines,  376 
Incandescent  igniter-tube  and  valve 


for  Otto  Crossley  1892  engine,  303, 

3°5 

Incandescent   igniter  tube  and  valve 
for  '  Stockport  Otto,'  319,  320 
-  —  used  m  starting  gear,  352 

Increase  in  economy,  value  of  com- 
pression, 318 

Increased     compression,      cause     of 
economy,  376-386 

Atkinson  on,  379 

—  economy  still  possible,  381-385 

Increase  in  initial  pressures,  385 

Increased  compression,  limits  of,  385 

Impulse  -  every  -  revolution     engines, 
future  of,  272 

Impulse-every-revolution  engines,  286 

Impulses  not  cut  out  in  Fielding  and 
Plan's  engines,  346 

Imperfect   mixture   in    Hornsby     oil 
engine,  418 

Improvements   desirable   in    oil    en- 
gines, 472 

Importance  of  shape  of  compression 
space,  378 

Isothermal  line,  40 


JACKET,  water,  use  of,  27 

Jameson,  Professor,  tests  of  Burt's 
compound  Otto,  338 

Jenkin,  Prof.  Fleeming,  on  compres- 
sion, 244 

on  future  of  gas  engine,  268 

Joule,  Dr. ,  hot  air  engine  of,  31 


KENNEDY,    A.    B.    W.,    Judge    in 
Society  of  Arts  tests,  279 


LAMP    to     heat    ignition    tube    in 

Samuelson  oil  engine,  419 
-  type   in  use   in   oil   engines,   the 

Etna,  43<-433. 

—  for  Crossley  oil  engine,  436 

Britannia  oil  engine,  451 

Lanchester,     F.     W.,     designer     of 

Barker  Otto  engine,  329 

—  and  D.  Clerk  self-starter,  349 

—  low-pressure  starter,  349-352 
Langen's,  Otto  and,  engine.  10,  136 
Largest  engine  manufactured,  block- 
port  Otto,  322-324 

Launches,  oil    engines  suitable  for, 

459 

Lebon's  engine,  5 

Legal  restrictions  upon  light  oils,  388 
Lencauchez  gas  producer,  367-370 


General  Index 


553 


LEN 


OIL 


Lencauchez    producer    gas,   analysis 

of,  370 
Lenoir  engine,  13,  15,  30,  118 

—  electrical  ignition,  203 
Light      spring      indicator     diagrams 

Crossley  Otto  engines,  308-309 
—  diagram  Crossley  scavenging 

engine,  316 

-    Stockport    Otto    engine, 

321 
Limitation    of   charge   in   oil   engine 

owing  to  heating,  465 
Limits  of  increased  compression,  385 

—  of  increase  in  gas  engine  efficiencies, 

383 

—  of  heat  evolution,  257-9 
London  coal  gas,  271 
Losses  in  gas  engines,  72,  78 

Low    pressure    starter,     Lanchester, 

349-3S2 

Lowest  flashing  point  of  oils,  396 
Lubrication,  235-238 


MALLARD  and  Le  Chatelier's  experi- 
ments, 85-87 

—  theory  of  limit,  258 
Maximum  compressions  possible,  385 
Mean   pressure  in  gas  engine    with 

producer  gas;  371 

Mean  pressures  less  in  oil  engines,  465 
Members  of  the  Olefine  series,  391 
Methods  still  open  to  obtain  increased 

economy,  381-386 
Mechanical  efficiency,  Otto,  174 
Midland  gas  engine,  The,  287 
Miller,  Mr.  T.  L. ,  tests  of  '  Fawcett ' 

gas  engine,  296 
Million  on  compression,  17 
—  gas  engine,  17 
Mixtures,  true  explosive,  79-82 

—  best  for  non-compression  engine, 
IOT 

—  dilute,  83 

Mixing  valve,  Clerk,  187 

—  Lenoir,  121 

—  Otto,  170 

Morrison,  Mr.  J.  W.,  tests  of  Barker 

Otto  engine,  329 
Motive  power,  gas  necessary  for,  355 


NAPHTHENE  isolated  from   Russian 

petroleum,  392 

Neutral  gases,  cushion  of,  247,  248 
Non-compression  engines— 

Barsanti  and  Matteucci's,  n 

BischofF  s,  132 


Non-compression  engines — 

Gillies',  151 

Hugon's,  20,  129 

Lenoir' s,  118 

Otto  and  Langen's,  136 

Street's,  i 

Wenham's,  35 

Wright's,  3 
Non-conducting  material  in  Capitaine 

vaporiser,  429 

Norton,  Prof.,  on  Ericcson,  26 
Notable  quantity,  246 


OILERS  Otto's,  236 

—  Clerk's,  238 

Oils,    American    petroleum,    compo- 
sition of,  389 

—  consumption  of  Pnestman  engine, 
414-416 

of  Hornsby  Akroyd  oil  engine, 

424-426 

of  Crossley  oil  engine,  437-439 

of  Fielding  and  Piatt  oil  engine, 

444 

in  Campbell  oil  engine,  448 

in  Britannia  oil  engine,  452 

—  in  Wells  Bros.'  oil  enyine,  458 
—  in   Weyman    and    Hitchcock's 
engine,  456 

—  distillation  of,  experiments  in,  400- 
406 

—  Pennsylvania   petroleum,    compo 
sition  of,  390 

—  petroleum  principally  used,  388 

—  petroleum   and  paraffin,    sold    in 
Britain,  394 

—  flashing  point  of,  394 

—  petroleum  and  shale  oils,    Robin- 
son's table  of,  397 

—  engines,  Messrs.  Wells  Bros.,  456- 

459 

—  engine,  the  Hock,  407 

the  Bray  ton,  407 

the  Spiel,  408 

—  the  Samuelson,  416-420 

—  the  Hornsby  Akroyd,  420-426 

—  the  Robey,  427 

—  the  Capitaine,  427-429 

the  Crossley  Otto,  430-439 

the  Tangye,  439~442 

—  Fielding  and  Platt's,  442-445 

—  the  Campbell,  445-449 
the  Britannia,  449-453 

—  Clarke,  Chapman  &  Co.'s,  453- 

455 

—  Weyman  and  Hitchcock's,  455- 

456 


554 


The  Gas  Engine 


OIL 


PET 


Oil  engine,  the  Daimler,  460-461 

—  difficulties  of,  462-473 

—  complete  combustion  necessary, 
388 

—  oil  used  in  early,  388 

—  early  forms  of,  407 

in  which  the  oil  is  sprayed  first, 

409-420 

—  method  of  spray  diffusion,  410 

—  the  Priestman,  410-416 

—  pump  used    in    Capitaine    oil 
engine,  429,  430 

—  with  external   vaporisers,   429- 

459 
• —  engine  lamp,  type  generally  in  use, 

43J-433 

—  supply  in  Crossley  oil  engine,  435 

—  in  Tangye  oil  engine,  441 

—  in  Campbell  oil  engine,  446 

—  feed  and  governing  in   Britannia 
oil  engine,  450 

—  supply  in  Wells  Bros.'  oil  engine, 
458 

—  engines    of    different    types    com- 
pared, 473 

—  engine  improvements,  473 
Olefine  series,  members  of,  391 
Otto's  engine,  136 

—  governor,  228,  232 
-< igniting  valve,  242 

—  starting  gear,  242 

—  tests  of,  172,  175,  180,  181 
Otto's  theory,  245 

Otto  and  Langen's  clutch,  136 
engine,  136 

—  M.  Tresca  on,  145 

—  patent,  expiration,  271 

—  Crossley  engines,  increase  in  eco- 
nomy of,  297 

—  power  of,  297 

—  engines  made  by  Messrs.  Crossley 
Bros.,  297-318 

—  Crossley    engine    1892 :    igniting 
valve  and  tube,  302,  305 

—  1892  :  governing  gear,  301- 

303 

—  tests  of,  308-389 

—  scavenging  engine,  309-317 
engines,    comparative   table   of 

old  and  new  types,  310 

—  —  scavenging  engine  test  by  Atkin- 
son, 318 

engines,   comparative   diagram 

of,  378 

oil  engine,  430-439 

cycle  engines,   leading  makers 

of,  272 

—  Stockport  engines,  318-324 


Otto    Stockport    engines,    tests    by 
Bellamy,  321,  322 
—  engine,  4oo-h.p.  largest  made, 
322,  324 

—  Tangye  engine,  329-332 

—  engine,  Burt's  patents,  339 

—  engines  by  Messrs.  Robey,  342-344 

—  high  speed  engine,  Burt's,  340-342 

—  engines  by  Messrs.    Fielding   and 
Platt,  346 

—  engines  by  Messrs.    Wells    Bros. , 
344-346 

—  Barker  engine,  324-329 

—  tests  at  Saltley  gas  works,  329 


PACKED  charge,  247 
Paraffin  oil,  Scotch  analysis  of,  414 
Papin's  expeiiments,  i 
Petroleum  engine,  Brayton's,  152 

—  early  forms  of,  407 

the  Hock,  407 

the  Bray  ton,  407 

—  the  Spiel,  408 

in  which  the  oil  is  first  sprayed, 

409-420 
method  of  spray  diffusion,  410 

—  the  Samuelson,  416-420 

-    spraying    device    in    Samuelson 
engine,  418 

—  vaporiser  in  Samuelson  oil  engine, 
419 

— T-  engine,  ignition  lamp  in  Samuelson , 
419 

—  engines,    the     Hornsby     Akroyd, 
420-426 

— •  —  vaporis:r  and  cylinder,  Hornsby 
Akroyd,  421 

—  the  Robey,  427 

—  the  Capitaine,  427-429 

—  with   external  vaporisers,   429- 

459 

—  the  Crossley  Otto,  430-439 

—  engine  lamp,  type  in  use,  431-433 

—  the  Tangye,  439~442 

—  P'ielding  and  Platt's,  442-445 

—  the  Campbell,  445-449 
the  Britannia,  449-453 

—  Clarke,  Chapman  &  Co. ,  453- 

455 

—  Weymanand  Hitchcock's,  455- 
456 

—  Wells  Bros.',  456-459 

—  The  Daimler,  460-461 

-  of  different   types  compared, 

473 

—  and   paraffin  oils,    chemistry    of, 
388-400 


General  Index 


555 


PET 


ROB 


Petroleums  principally  used,  388 

—  crude,  388,  389 

—  American,  composition  of,  389 
Pennsylvania  petroleum,  composition 

of,  390 

Petroleum,    Russian,    naphthenes  in» 
392 

—  ether  and  spirit,  393 

—  and  shale  oils,   British,   Professor 
Robinson's  experiments  in,  397 

—  and  paraffin  burning  oils   sold  in 
Britain,  394-398 

—  flashing  point  of,  394 

—  vaporised  with  air,  400 

—  oils,    distilling   by   air   or   steam, 

405 

—  oils,  experiments  in  distillation  of, 
400-406 

—  heavy  oil,  decomposition  of,  403 
Pinkney's  governor,  156 

—  patent  Tangye  oil  engine,  439 
Piston   velocity    in     Lenoir    engine, 

MS 

in  Otto  engine,  172,  175 

—  in  Otto   and   Langen  engine, 

144 
-  speed  old  and  new  type  Otto 

Crossley  engines,  310 

—  valve  in  Fawcett  gas  engine,  295 

—  valves  in  Burl's  Otto  engines,  339 
340 

Ports,  action  of  excessive  surface  in, 

3°7 
Ports  and  passages,  design  of,  325, 

328 
Possible  efficiencies  in  gas  engines, 

-,86 
Priestman  oil  engine  vaporiser  and 

cylinder,  411 

—  410-416 

—  spraying   jet  and  air  valve, 
412 

—  governor  gear,  414 

—  tests  of  by  Unwin,  414-416 
Premature  ignitions,  cause  of,  306 

—  explosions  avoided  by  scavenging, 
380 

Pressure,  effect  of  heating  oil  under, 
403 

—  advantage  of,  in  vapour  jet,  437 

—  and  temperature,  38,  107 

—  produced  by  explosion,  99-101 

—  if  no  loss  existed,  104-105 
Products  of  combustion,  82,  109 

—  proportion  in   Hugon    engine, 
J3i 

in  Lenoir  engine,  131 

in  Otto  engine,  173 


Products  of  combustion  totally  ex- 
pelled in  Atkinson  Cycle  engine,  283 

Producer  gas,  chemical  reactions  in 
making.  356-359 

—  Dowson  gas,  359-367 

—  Lencauchez  gas,  367-370 

—  Dowson  gas,  consumption  of  fuel, 

371 
-  Taylor's    gas,  test  with   loo-h.p. 

engine,  373 

Pump  for  oil  used  in  Capita!  ne  oil 
engine,  429 

—  and  oil  supply  in  Crossley  engine, 

435 
Pure  mixture  obtained  by  scavenging, 

3*4 


RANKINE  on  air  engine,  24 

—  available  heat,  112 

science  of  thermodynamics, 

36 

Ratio  of  air  to  gas,  in  explosive  mix- 
tures, 99-101 

—  in  Clerk's  engine,  193,  195 
in  Lenoir's  engine,  128 

—  in  Otto's  engine,  173,  176 
in      Otto      and      Langen's 

engine,  14 
Ratio  of  compression  space  : 

in  Clerk's  engine,  192 

-in  Million's  engine,  17 

—  in  Otto's  engine,  172,  175 

—  of  air  to   gas.      Atkinson  engine, 
Society  of  Arts  tests,  282 

—  of    specific    heats.        Erroneous 
assumption   by  Society   of  Arts  in 
their  tests,  281-282 

Reactions,  chemical,  in  gas  produc- 
ing, 356-359 

Reduction  in  gas  consumption  due 
to  increased  compression,  318 

Redwood  and  Dewar's  method  of  oil 
distillation,  404 

Red-hot  surfaces  in  vaporisers  a 
mistake,  406 

Relative  cost  of  power,  steam  and 
gas  engine,  354 

Reservoir,  use  of,    in   starting  gear, 

Richards'  analysis  of  Lencauchez  gas, 

370 
Richardson  and  Norris,  the  Robey  oil 

engine,  427 
Robson's  engine,  195 
Robinson,  Professor,   experiments  on 

British  sold  petroleum  and    shale 

oils,  397 


556 


The  Gas  Engine 


ROB 


TEM 


Robey's  Otto  engine,  3^2-344 

Robey  oil  engine,  427 

Root's      patent     oil      engine       (the 

Britannia),  449-453 
Rowden,     Professor   W.    J. ,    on   the 

Burt  compound  engine,  333 
• test  of  Burt's  compound  Otto, 

338 
Royal   daylight   oil,    distillation    of, 

401 
Russoline    oil    analysis    by    Wilson, 

425 


SALTLEY  gas  works  test  of  Barker 

Otto  engine,  329 
Samuelson  oil  engine,  416-420 
Scavenging    engine,     Crossley    Otto 

engine,  309-317 

—  advantages  of,  380 

—  arrangements  in  Wells  Bros.'  Otto, 

344 

—  economy  due  to,  379 

Scotch     paraffin     oil,     analysis     of, 

414 

Schmidt  on  compression,  16 
Schottler  on  stratification,  256 

—  tests  of  Otto  engine,  180 
Self-starting     gear,      necessity     for, 

347 
Shale  and  petroleum  oils,  Robinson's 

table  of,  397 
Silencer    for    Stockport    '  Otto '    air 

suction,  318 
Simon's    '  Trent '    gas   engine,    287- 

290 

Simplest  gas  engine  starter,  350 
Simon's  steam  gas  engine,  32,  163 
Slow  combustion,  Bousfield  on,  250 

—  Imray  on,  250 

—  Otto  on,  246 

—  Slaby  on,  247-9 

Slide  valves,  defects  of,  304-305 
Spangler,  Mr.  H.  W. ,  test  of  ico-h.p. 

engine  and  gas  producer,  373 
Specific   heats,    ratio    of.     Erroneous 

assumption    of    Society    of    Arts 

Judges,  281-282 
Specific  heat  of  gases,  90 
Spiel  petroleum  engine,  408 
Spray  diffuser,  type  of  in  use  in  oil 

engines,  410 
Spray  lamp    in    Samuelson    engine, 

419 
Spraying  jet  and  air  valve,  Priestman, 

412 

—  device  in  Samuelson  engine,  418 

—  method  in  oil  engines,  464 


Starting  gear,  Clerk's,  239 

—  Otto's,  242 

—  for  Stockport  '  Otto,'  320 

—  the  Clerk  Crossley,  347-348 

— •  —  the  Clerk  Lanchester,   348-349 

—  Lanchester   low-pressure,   349— 
352 

on    Stockport    Otto     engines, 

352 
Tangye  Otto  engines,  352 

—  —   Fielding    &    Platt's    Otto 
engines,  353 

—  Samuelson  oil  engine,  420 

—  Hornsby     Akroyd     engine,     420, 
423 

—  the  Capitaine  oil  engine,  428 

—  the  Etna  oil  engine  lamp,  433 

—  the  Tangye  oil  engine,  439 

—  Fielding  &  Platt's  oil  engine,  443 

—  lamp  in  Britannia  oil  engine,  451 
Stockport  Otto  engines,  tests  by  Mr. 

Bellamy,  321,  322 

—  3l8~324 

40o-h.p.  engine,  largest  made, 

322-324 

Stockport  engine,  197 
Stratification,  Bousfield  on,  250 

—  experiments   in   support   of,    249, 
250 

—  fallacy  of,  254,  255,  256 

—  Lenoir  on,  16 

—  Otto  on,  246 

—  Schottler  on,  256 

—  Slaby  on,  247,  248 
Street's  gas  engine  pump,  i 


TABLE  of  efficiencies,  68 
Tandem  gas  engine,  Stockport  Otto, 
400-h.p.,  322-324 

—  engine,    Burt's    high-speed   Otto, 

34° 

Messrs.  Fielding  &  Platt's,  346 

Tangye' s  Otto  engine,  329-332 

—  starting  gear,  352 

—  oil  engine,  439-442 

—  engine  (Robson's),  195 
Tar  in  producer  gas,  370 
Taylor's  gas  producer,  tests  of,  373 
Temperature       of      combustion      in 

Brayton  engine,  161 

exhaust  in  Lenoir's  engine,  122 

in  Otto  engine,  173,  176 

Temperatures  of  explosion,  107-111 

in  Lenoir's  engine,  125,  126 

in  Otto  and  Langen  engine, 

146,  149 
in  Otto  engine,  177,  179 


General  Index 


557 


TEM 

Temperatures  of  air  supply  in  Priest- 
man  oil  engine,  464 

,  walls  of  combustion  chamber  in 

oil  engine,  468 

Tests  of  4-n.h.p.,  Atkinson  Cycle 
engine,  278 

modern  Crossley  '  Otto  '  engine 

1892,  308 

. slide  valve  Otto  engine  1881, 

309 
Crossley       Otto        scavenging 

engine  by  D.  Clerk,  316 
—  Crossley  Otto  engine  by  Society 

of  Arts,  317 

-  —  —  scavenging  engine  by  Atkin- 
son, 318 
— •  Stockport     Otto    engine    with 

increased  compression,  321,  322 
Barker  Otto  engine  at  Saltley 

gas  works,  329,  330 
Tangye's     Otto     engine,      35- 

n.h.p.,  332 
Burt's      compound     Otto     by 

Jameson,  338 

•  Rowden,  338 

a  6-b.h.p.    Wells   Bros.1    Otto 

engine,  346 
Dowson  producer  and  6o-h.p. 

Otto  engine,  371 
and     loo-h.p.      complex 

engine,  373 

—  —  loo-h.p.    Otto    and    gas    pro- 
ducer, 373 

Otto  engine  and  Dowson  pro- 
ducer by  D.  Clerk,  374 
Testing    the  flashing  point   of  oils, 

394-395 

Tests  and  oil  consumption  in  Priest- 
man  oil  engine,  414-416 

of   Hornsby    Akroyd   oil 

engine,  424-426 

—  of  Capitaine  oil  engine,  428 

—  and  oil  consumption    of  Crossley 
oil  engine,  437-439 

—  of  Fielding  &  Plait's  oil 
engine,  444 

in  Campbell  oil  engine, 

448 

Britannia  oil  engine,  452 

— in  Weyman  &  Hitchcock 

engine,  456 

—  in  Wells  Bros.'  oil   engine, 
458 

Theoretic  efficiencies,  68 
Theories  of  action  in  cylinder,  243 
Theoretical  riagram,    adiabatic  and 

isothermal  lines,  384 
Theory  of  vaporising  oil,  398-406 


UNW 

Thermodynamics  of  the  gas  engine, 

36 
Thermal  units  in  Russoline  and  Royal 

daylight  oils,  416 
Throttling  in  entering  gases,  305 
Thurston's     experiments     on     Otto 
engine,  175 
—  on  dissociation,  178 
Time  taken  to  start  Hornsby  Akroyd 
oil  engine,  424 

—  Capitaine  oil  engine,  428 

Crossley  oil  engine,  437 

Fielding     &     Platt's    oil 

engine,  444 

Britannia  oil  engine,  453 

Timing  valve,  absence  of,  in   barker 

Otto,  328 
Tower,   Mr.    Beauchamp,  Judge  in 

Society  of  Arts  tests,  279 
Tresca's      experiments     in     Lenoir 
engine,  123 

in  Hugon  engine,  132 

Otto  and  Langen  engine,  141 

theories  of  Otto    and  Langen 

engine,  145 

Trent  gas  engine,  the,  287-290 
Trunk  piston  of  two  diameters,  287 
Type,  first  description  of  perfect  cycle, 
29 

—  second  description  of  perfect  cycle, 

3° 

—  third  description  of  perfect   cycle, 
32 

—  i  A,  description  of  perfect  cycle, 

34 

—  i  : 

Lenoir  engine,  118 
Hugon  engine,  129 
Bischoff  engine,  132 

—  2  : 

Brayton  petroleum  engine,  152 
Simon  engine,  163 

Atkinson  engine,  199 
Clerk  engine,  184 
Otto  engine,  166 
Stockport  engine,  197 
Tangye  engine,  197 

—  i  A: 

Gillies'  engine,  151 
Otto  and  Langen  engine,  136 
Types  of  oil  engines,  408-409 

—  of   vaporiser    dependent  on    oil, 
398 


UNWIN,  Professor,  tests  of  Atkinson 
'  Cycle '  engine,  278-279 


558 


The  Gas  Engine 


UNW 


WRI 


Unwin,  Professor,  tests  of  Priestman 

oilengine,  414-416 
'  Utilite'  Atkinson  gas  engine,  284- 

286 


VACUUM  gas  engine.  2 

—  partial,  induced  in  exhaust  pipe, 

3*3 

Valve-gearing    '  Trent  '  gas    engine, 
288 

—  of   '  Stockport   Otto  '     engine, 
319-320 

--  of  400  h.p.  'Stockport    Otto,' 

324-325 

--  and    arrangements    of   Barker 
'Otto,'  326-327 

—  in  Burl's  high  speed  Otto  en- 


gne, 340-341 
al 


Valveless  gas  engine,    'The    Day,' 

290 
Valve  setting    in  Crossley  Otto  sca- 

venging engine,  315 
Vaporiser    surfaces    should    not    he 

red  hot,  406 

—  and  cylinder    of    Priestman     oil 
engine,  411 

—  in  Samuelson  oil  engine,  419 

—  and    cylinder     Hornsby     Akroyd 
engine,  421 

•  —  and      combustion    chamber      of 
Robey  oil  engine,  427 

—  Capitaine    oil   engine, 
'429 

—  in  Crossley  oil  engine,  434 

—  in  Tangye  oil  engine,  440 

—  and     ignition   tube   combined    in 
Fielding  £  Platt  oil  engine,  442 

—  in  Campbell  oil  engine,  445 

—  and    ignition     in      Britannia     oil 
engine,  449 

Vaporiser,   type  of,    dependent    on 

oil,  398 
Vaporising  arrangements  in  Clarke  & 

Chapman's  oil  engine,  453 

—  Weyman   &  Hitchcock    en- 

gine, 455 

—  in  external  vessel,  method  of,  470 

—  light  oils,  387 

Vaporising  petroleum  with  air,  400 

—  and    decomposing    methods     of, 
398-406 

Vapour  tension  of  water,  398-399 


Varying    ignition     in    Barker     Otto 

without  timing  valve,  328 
Velocity  of  flame  propagation,  85 

—  entering  mixture  in  early  Otto 
Crossley  engines,  305 

—  exhaust     gases    in     new     type 
Otto,  306 

—  old  type  Otto,  306 
entering    mixture    in     modern 

Otto  Crossley  engine,  306 
Volumes    and     relative    weights     of 
gases,  8 1 

—  of     Deutz    coal    gas, 
172 

—  of  Hoboken   coal  gas, 
176 

Volume  of  air  required  in  combus- 
tion of  Dowson  gas,  365 

Volatile  liquids  produced  from 
petroleum,  393 


WALLS    of    combustion     chamber, 

temperature  of,  468 
Water  jacket,  use  of,  27 

—  evaporated  by  air,  399 

—  gas  for  gas  engines,  370 

—  jacket     heat     lost    in    Atkinson's 
'  Cycle '  engine,  278 

—  Priestman  oil   engine, 

415 

—  vapour  tension,  398,  399 
Wave  explosion,  114 

Waves  of  pressure  or  oscillations  in 

exhaust  pipe,  313 
Wedding  on  dissociation,  183 
Weights    and    volume,    relative,    of 

gases,  8  r 

—  molecular,  of  gases,  81,  82 
Wells  Bros.'  Otto  engine,  344-346 

—  oil  engine,  459 
Weyman  £  Hitchcock's   oil   engine, 

455-456 

Wenham  s  engines,  25,  35 
Whole   air    charge    drawn    through 

vaporiser  in  oil  engines,  471 
Wiltz  on  compression,  244 

—  Professor  A.,    test  of   a  loc-h.p. 
engine  and  gas  producer,  373 

Wilson,  Mr.  C.  J.,  analysis  of  Scotch 
paraffin  oil,  414 

analysis  of  Russoline  oil,  425 

Wright's  engine,  3 


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